WELCOME to the anvilfire Guru's Den - V. 3.3

THIS is a forum for questions and answers about blacksmithing and general metalworking. Ask the Guru any reasonable question and he or one of his helpers will answer your question, find someone that can, OR research the question for you.

This is an archive of posts from August 1 - 7, 2009 on the Guru's Den
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Guru, anyone, talking about subing out things like large quantities of identical parts, what do you think about the smaller scale cnc plasma torch machines? I'm thinking of something like a PlasmaCAM or Torch Mate type of set up.
With these you buy the ways/frame, servoes, drivers and machine controle interface with the required software, from the manufacturer and then you must supply the plasma torch and a compatable computer system to run it on.
I was looking very seriously at the PlasmaCAM set up for use at another shop I used to work at and when I left there I thought about getting the set up for myself if I could find the work to make it pay.
Full up, three years ago, that would have run between $15,000 to $17.000 and, if you can do more than just the prepackaged "clip art" stuff that comes with it, I think it would have some good prospects.
   - merl - Friday, 07/31/09 23:56:12 EDT

Merl, Unless you have the work for such a machine then you are probably better off using a local service house. You can still make the drawings yourself. After a couple tests with your vendor it will go very smoothly. I used to make and edit drawings for an engraver that took the exact same DFX file format as the cutting tables. We rarely had glitches that had to be changed.

Besides the cutting table you will need a good crane or hoist, preferably a rectilinear hoist unless you are going to do nothing heavier than 1/16" (2mm) and even then large sheets are hard to handle. You will also need stock racks for sheet. And if you do production work for others you will need a fork lift to handle the barrels full of parts. . . and space for all the above.

A friend of mine forges furniture feet from blanks plasma cut out of 1/2" steel plate. The blanks cost less than a dollar by the thousands. . . It would take YEARS maybe decades to pay for any machine capable of this work. The same fellow used to painstakingly make steel templates for a magnetic wheel torch system to cut similar blanks. He can get several thousand blanks cut by someone else for less than his in-house template cost. AND if a digital template is not right then it only takes minutes to make the change and email the file.

This is a competitive business that can save you a lot of money. If you want to go into it then you should do so seriously. Many of the people in the business warehouse tons of plate OR are located convieniently to a Steel Service Center.

For the average blacksmith shop you are either better off to cut it by hand, OR to sub it out. Some folks are artists with a plasma torch and unless they are doing production work are much better off doing the job by hand. To keep the hand made look on large jobs you can provide patterns with variations such as leaves of different sizes or maturity. After hand working them nobody would know the difference.

You ever look at the shapes of Hardies chicken nuggets? They all look like random lumps don't they? There are exactly FOUR shapes, no more. You can do the same with flowers, leaves or other elements where they are all supposed to look different. Some small variations in the patterns, and some hand work and it would take a very dedicated student of the art to figure out how many blank shapes you used . .
   - guru - Saturday, 08/01/09 02:23:42 EDT


Before you consider getting the PlasmaCam, you might want to read here: http://www.artmetal.com/blog/studio23/2007/07/cnc_plasmacutter_torchmate_vs_plasma_cam

There seem to be some issues with the entry-level CNC plasma cutters, from what I've read in that thread, at least. If you're at all serious about getting one, I'd definitely suggest asking Ries Niemi for his advice.
   vicopper - Saturday, 08/01/09 03:13:33 EDT

Guru, how many Hardies Chicken Nuggets did you have to eat to determine there were only 4 basic shapes?
   quenchcrack - Saturday, 08/01/09 09:20:16 EDT

They are well distributed (probably in sets of 4). Only a couple six packs but I've eaten many more. They look absolutely randomly shaped unless you pay attention. I'm sure someone did a study that determined that you needed no more than four.
   - guru - Saturday, 08/01/09 10:03:41 EDT

Using the Guru/Hardies Theory of Random Distribution in Edible Shapes (the GHTRDES), we can see that all potato chips start life as pretty much the same pre-form, but after hot-working appear random. I've eaten many bags of same before postulating this corollary.
   - grant - Saturday, 08/01/09 11:29:59 EDT

Well, assuming there are 6 nuggets per serving, and 4 shapes, we get 6 x 4 = 24 possible combinations of the 4 shapes in a 6 piece serving. One cannot calculate the number of servings needed to finally recognize the 4 basic shapes. However, the Guru is very observant and probably a recognized expert on nugget shapes. Grant, most of the potato chip bags I get seem to have been super-randomized by heavy handed clerks and careless shoppers. I thought about super-gluing them back to original shape but found it too time consuming. I think I'll stick to chicken nuggets.
   quenchcrack - Saturday, 08/01/09 15:07:28 EDT

Ah yes, Sir Quenchcrack! Flexable strength VS Ridgid. Good point, I'l get the focus group division on that one right away.

Grant, Center for the Study of Possible Conspiracies in Food Preparation.
   - grant - Saturday, 08/01/09 16:47:06 EDT

I think I'll study the "What's in the Bottom of My Beer Can" conspiracy for the rest of the afternoon. Hold my calls, I'm doing research!
   - grant - Saturday, 08/01/09 16:50:57 EDT

Grant, I too think I will do some research, on the bottom of a beer can or two as well.
   ptree - Saturday, 08/01/09 19:28:00 EDT

Hi Bruce, we have now excavated the bottom cavity of the forge - we found evidence of unburnt charcoal so believe it was a charcoal store. Although we did find evidence of molten metal it was to the rear and we suspect it fell through the broken stone slab when we cleaned out the fire pit. We feel it is unlikely that unspent charcoal fell from the fire pit. Also, we found a large lump of molten metal in the side of the fire pit attached to what we think is the fire proof lining - it reaffirms our view that the fire pit was lined with 3 or 4 inches of lime mortar (rather than clay). I have posted some more photos at http://www.flickr.com/photos/40413182@N02/collections/72157621794419003/

regards, John
   - John - Sunday, 08/02/09 10:05:32 EDT

I dont quite agree with the guru about plasma cutting systems- I bought mine, in 1992, for about ten grand, and the first job I did with it more than paid for it. Yes, it was a major job, a very large and intricate fence, but every year since then, I have probably made the machines cost back from it.

Mine, however, is an optical trace machine- no computer. Mainly because, way back then, a computer would have been an extra $10k to $15k- there were no programs to run em on a PC, nor were PC's capable at that time.
I actually like the paper pattern system pretty well, and have not been tempted to switch to digital, but I seldom do runs of more than 200 or one part, and its easy enough to draw a couple dozen of the same shape, and then just slide the steel over for multiple cuts.

I must say I am a bit dubious of plasma cam- its just not built very sturdily. But many owners seem to like them.

Many of the Guru's points are right on though- you really do need a forklift, and a big stock rack, to run one of these machines, along with a big compressor, (my 7 1/2Hp large industrial model runs pretty much continuously when I am cutting, with a 90 gallon tank) and you need really good fume removal- them suckers are dirty!
I run a whole shop filtering system, and a point of cut fume evacuation hose, along with using a homemade water table to catch sparks and grit. And the ceiling is still brown...

If you do large or complicated custom work- then it makes sense to have your own machine. If, as the Guru suggests, you use 3 or 5 of the same simple shape, by the hundreds or thousands, then by all means, job it out.
But I often do pieces that require unique 4' x 8' drawings, which will be cut once. My local cutting houses charge $35/hr and up for computer work, to make these drawings, even from DWF files, work on their software, and its not uncommon for something like a human figure, which will be totally mangled by autocad, to require an hour or three of fixup.
Some of my designs would have cost me quite a pretty penny in computer time, before we even got to cutting.

Another reason to own your own tools, though, is something I was discussing with Grant last week- and that is, unless you have it in front of you, you cant find out all the creative ways it was never intended to be used, that result in great tricks and products that nobody else has figured out yet.
With a plasma cutter in house, if the first piece is slightly wrong, you change the design, and cut another one- til you like it. Not usually practical with sending it out.
Also the lead time, or lack of it, is a big factor for me. My local waterjet and plasma houses usually run a week to three in back order time- whereas I can trace a part, draw a pattern, cut it out, and be welding or forging it in about 15 minutes.

I can also make ONE of something, and, if I like it, or it sells, make 100 more. Or, maybe, never make another one. I have rolls and rolls of patterns, the analog equivalent of computer programs, for all kinds of shapes, from circles to animal heads, and often will drag one out and cut one that hasnt been seen for ten years...

In general, I find that good blacksmiths are like jazz musicians- they improvise- and that means that having to draw a design, and wait 2 weeks for somebody to cut it, ties you down in ways that I, personally, would not like. I need to be able to change sizes, shapes, orientations, to toss aside ideas and try new ones, and so on- all of which means I LOVE having my own machines, in the shop, no matter what type of machine, as opposed to farming stuff out.

Another thing Grant and I agreed on was that virtually every time we bought a machine, we found new and unforseen ways for it to make us money- ideas we never would have had if we were just paying somebody else to make a part.
   - Ries - Sunday, 08/02/09 12:59:13 EDT


I continue to look at your photos, but it is difficult for me to get a perspective of the hearth setup. This rectangular, horizontal stone slab in front of the worker appears to be elevated above the hearth stone, the latter having the slit and "broken corner." In your photos, is the rectangular stone is hiding the hearth stone from view? If so, how much lower is the hearth stone than the rectangular one?

As a working smith, the near, rectangular stone appears to be an elevated obstruction; ie., to be in the way of getting the work in and out of the fire.

In thinking about the hearth stone proper, The central slit may be accidental, but it would provide a little air to the fire from below, and that helps to keep the fire going, particularly when the fire is left for a period and is not in use, lunchtime for example. For instance, in our bottom blast coal forges, we do three things to keep the fire coals hot when the blast is not being used. We bank the hot coals with fresh coal, perhaps covering the fire with an inch or so of the coal. We prop open the ash dump door with the fire rake, thus allowing air to get to the fire from below. We take a 3/4"D x 6" wooden stick and insert it into the center of the fire vertically.

I would believe that the broken corner of the hearth stone is not desirable. The fire is built by "coning it up," meaning that the worker obtains a conical appearing fire, the coal or coke taking its respective angle of repose. It would be easy to allow unburned coal to fall down the hearth corner, because that coal is out on the periphery of the central, hot spot of the fire. The work being placed in and out does disturb the fire to a degree, and the worker doesn't want the good coal to fall off the hearth by gravity.

In terms of measurement, the bellows tuyere tube enters through the wall; what is its relationship to the hearth?
   Frank Turley - Sunday, 08/02/09 13:57:08 EDT

Where you find things in a forge shop is not necessarily where they started. In a dirt floor shop fuel and ashes get kicked around all over. If the smith is not a conscientious housekeeper (few are) then loose fuel, ashes, scale, debris and small tools end up on the floor and shuffled about under foot.

A friend of mine had a cramped shop in a basement location with a gravel floor. When he went to move after a busy 8 to 9 year occupation they "mined" a full pickup truck load of old rusted tools out of the gravel floor. Tools that had fallen off the forge, tools that had fallen through the holes in the weld-platen bench, tools dropped while working as is common in hot work.

My point is that almost anything in the shop or forge can be found in small traces almost anywhere in the shop, not particularly where you expect them.

Fuel caches are dirty. Both charcoal and coal have significant dust that will filter down in the floor and soil leaving more than just a trace in storage places.

While fire scale (burnt iron) is found everywhere in a forge shop it accumulates significantly around the anvil location. Scale rings including many small bits of metal are persistent in soil floors and one of the best indicators of forge activity and layout.

While soil floors can serve as records of past activity they can also erase it. Change of ownership, cleanup operations, weathering, flooding. It can make an archeologists job very difficult.

Forge at Old Millstone Forge
Old Millstone Forge - Click for enlargement
This forge said to be about 200 years old or more has seen many changes. Currently the bellows has been bypassed and a commercial bottom blast tuyere has been installed. But originally this would have been a charcoal forge. Note the wood hearth and built in wood shelf. Also notice the coal and ash going everywhere. It helps to know what something might have looked like in operation. . .
   - guru - Sunday, 08/02/09 15:27:55 EDT

Cutting Tables, CAD and New Equipment: As a tool junky I too see every new machine as a creative opportunity. But there are still times when subbing out stock cutting jobs is most efficient. However, that is subject to availability of services.

The CAD is something you need to learn to deal with on your end and provide files to the service house. I have never had any trouble with my DXF files but you need to know that AutoCAD, the "owner" of the DXF format handles it worse than anyone else. Its like Microsoft and rich text, every other vendor does a better job than Microsoft products in creating the files. Same with DXF's. My 10 year old copy of DesignCAD (no longer supported) produces great DXF's.

Generally all curves and predefined shapes must be converted to vectors. This changes curves into many short straight lines. Some cutting system reserve colors such a green to be ignored for notes, reference dimensions and such.

I found that if I export a vector converted file to DXF and then import it back to the native system and it looks as expected then everything is right and the DXF is good to send out.

There are basic CAD issues that generally are not taught or written about well that must be addressed. You cannot just create lines willy-nilly and have a good file. All connecting points between lines MUST be true perfect matches. They cannot just LOOK like they meet. No amount of zooming and mousing around will make it so. Every connecting point in a proper CAD file is aligned using a gravity or "snap" command that gives both lines the same numerical end point to within the last decimal point of the system files. If lines do not meet, the cut stops.

Many CAD jockies do not understand these simple basics and end up paying someone else a lot to have their files cleaned up. I know because I used to clean up others drawings for an engraver. It generally took two simple steps. 1) Convert everything including text to vectors, 2) Insure that connecting lines connect. Number 2 did not make any difference in engraving but it does in cutting. It can require making a new drawing to correct line end errors.

Learn to make good template files for your service house and you may find that the backups are in the CAD department, not on the cutting table. But you have to work with your vendor.

The big advantage to knowing how to make proper CAD cutting templates is for those high production jobs that you do not want in your shop, the BIG job that doesn't fit your machinery AND the odd job that must go to laser or waterjet for some technical reason.

Creative Use:

I agree there are LOTs of non-standard uses for every machine. However, the folks that have the imagination PLUS the mechanical ability generally do not need to be advised about the value or possibilities of a machine (or having machinery). But you also need to know when to send jobs to others.

Flame cutting tables (oxy-fuel) can be used for three dimensional cutting but it is rarely done. Same for track cutters (straight line). Work is cut on one axis, flipped then cut on the other. There are alignment issues but small commercial torches will cut up to 6". You can sculpt some pretty significant stuff from 6" plate. . . Stuff too heavy to forge without a BIG hammer.

Engine Lathes have been applied to an amazing number of tasks (besides the usual and those listed in the Lathe article). Coil and spring winding, powering roll benders, straight line flame cutting, metal spinning (commercial and artistic), twisting small bar, spray metallizing round parts, rotating parts while using and angle grinder to shape and polish, scribing divider marks, tumbling small parts, driving a flexible shaft (for die grinder work).

I made a small belt driven drill to fit in the tail stock for drilling and countersinking both sides of a part held in on the carriage. Clamp the part once, drill right, drill left, change the part. . . Clamp once and the holes line up. More than halved the time to make the parts.

We made a little adapter to hold a Dremel tool on a small lathe for tool post grinding. Used it to make some little hardened cams and to dress the lathe centers.

Dremel tools have been adapted for all kinds of uses by luthiers for miniature routing and milling, jig drilling, cut off work.

Milling machines have been used with a fly cutter to create textured surfaces in jewelery dies. . .

Shapers Have been used with grinders for rough surface grinding, a heavy duty parts feeder, power shears, making lap joints in railing parts for clean parts.

Drill Presses have many uses besides drilling and boring including vertical drum sanding, spot finishing, paint, clay or slurry mixing, VERY light pressing, hand turning (similar to a wood lathe), polishing, driving a flexible shaft (for die grinder work).

My oldest 20" drill press is now scrap since I cannibalized it for parts for better machines. But it will have yet another life as a vise stand. It could also be used as an adjustable height stock stand. But I think it will make a pretty good vise stand with its swing arm, heavy rotating table and adjustable height. Shafts, pulleys, gears (that aren't worn out) will go on the scrap pile for later use. .

For over 100 years publishers such as Industrial Press have been putting out books full of "shop kinks" with hundreds of useful (to some) ideas gleaned from machinists and shop operators. Some have become standard practice, some are out dated but many are quite interesting. While I've picked up a trick or two from the couple I've read most of the creative machine applications I've used came from a need and my own imagination. I suspect that is where most come from, the user's imagination based on prior experience.
   - guru - Sunday, 08/02/09 20:03:20 EDT

Yeah Ries, I've bought many a "solution looking for a problem". With only one notable exception, they have all made me money. One machine I bought 16 years ago was a powered fly press or "friction screw press". It sat for a little while and I played with it squishing this and that until I had a feel for what it was good for. Decided it would be pretty good at making tong with progressive dies. Anyone know the "rest of the story"? Well, 100,000 pair of tongs later, I'd have to say buying that machine was a "smart"(fortuitous?)decision.

The one exception is O.K too. 'Bout ten years ago I decided that I would get into the rolled products business, doing real "gooshy" stuff, not like the flatbar some were doing. Got all excited about it and Spent more than $100,000.00 on my brainstorm. Well, when I get myself convinced of something, watch out. Got a nice #4 National rolling machine with 10 inch rolls, wow, 3 feet per second rolling bar. Then I needed a 4-axis CNC mill so I bought a Haas VF-2, $70,000.00 with all the bell and whistles. Well, you know, these thing don't come with anything, sorta like a Christmas tree. So, another $10,000.00 for ornaments (tooling). Well, ya can't program very complex rolls without software, another $10,000.00. (am I boring you yet?). Turns out that these things eat up hot steel like a white shark goes thru tuna! And ya gotta heat really long pieces too. And then there's marketing the products. Well, in the mean time, my swage business skyrocketed because the Haas and the software (and my EDM) made it possible to have an idea in the morning and be making parts in the afternoon! So........ anyone interested in a really nice 16,000 pound roll forging machine?
   - grant - Sunday, 08/02/09 20:20:16 EDT

Grant, Love ya baby. You just told me exactly what I always belived about you. You are just a bigger boy playing with big boys machines.

I would have loved that roll forging machine years ago when I still had money to play with
   Charlotte - Sunday, 08/02/09 20:27:04 EDT

Oh yeah, I buy toys and THEN find ways they can make me money, and NO I didn't learn THAT in Harvard Business School!
   - grant - Sunday, 08/02/09 20:37:31 EDT

Big Ugly Machines. . . Grant managed to sell a number of those big presses to other folks and not a one put them to use. One replaced theirs with a hydraulic press of about the same capacity. I think the flypress would have done the job and much more quietly.

I'm sure I could put one to work doing SOMETHING.
   - guru - Sunday, 08/02/09 21:06:33 EDT

Tools + imagination = success. Without imagination, no tool is any good. I sold a number (maybe twenty)of those machines and many are used nearly daily, some languish. Only three went out to your end of the country, sad.
   - grant - Sunday, 08/02/09 21:21:08 EDT

We had an optical line tracer oxy/fuel plate cutter at the auto frame plant. I was told that when the plant closed in 2000 it sold for very little money. While a machine like this could easily be converted to plasma, and would be handy to own, it's flor space requirements were enormous. The machine was sized for full sheets of plate, 10' x 20'. The cutting table rolled out from under the machine so plate could be handled with a bridge crane. The steel storage yard to store stacks of plate in common sizes from 1/2" to 12" thick, plus the shed that housed the machine covered several thousand Sq Ft. and had it's own 20 ton bridge crane. The bulk oxygen storage tank space requirement was not included in the above space estimate. The price of the machine at auction was only the tip of the iceberg of replicating the "burniing Shed" operation as it was set up at the plant.
   - Dave Boyer - Sunday, 08/02/09 21:21:25 EDT

Grant, Those machines have since gone on to other people who may be using them. I had a chance at one but it was not conducive to my current situation. If I had been making a living in blacksmithing I would have found a way. . .

When my local small steel outlet closed down I bought their track torch setup. I traded the tractor and the track to a friend and kept the machine torches. The smaller machine torch fit a Hob-O circle cutter that I purchased later and it also works on a lathe where I could make cuts in plate up to 6" (with extra cylinders) about 5 feet long on my current lathes. I've used the lathe setup a couple times on 3/4", 1" and 2" plate. Cuts were as smooth and straight as the best flame cutting. The rig doesn't take up a big part of the shop as it stores on a shelf and stock is just supported on some heavy steel supports that are handy for many things. The Hob-O which cuts circles also stores on a shelf and is portable.

The above is not a production or common use setup. But if I need to do a pretty job cutting up some heavy steel its there to use once in a while. Meanwhile the lathe is useful for other things and the space near it is not permanently tied up with a cutting table.

One job that can be done pretty slick with a machine torch is cut wedges. You can flame cut them as accurate as your setup and if you are using a lathe with a taper attachment the tape can be VERY accurate. The raw wedges can be hand dressed or finish ground taking off little material. Beats the heck out of anything other than a big saw. If you don't have one. . . then the torch works.

   - guru - Sunday, 08/02/09 22:59:12 EDT

In House Plasma Cutting:
Ries, I have to agree with your "pro" reasoning completely. Having the machines in your own shop and at your disposal at any time is what I'm looking for. I don't wonder if I could find any use for them, I know I can. I wonder about the specific machines them self.
I have to agree about the PlasmaCAM machine, it does look kind of light and maybe not up to production but, I like the operator controles and they run on Windows XP PRO, that I'm already useing.
I like the sound of your optical tracing machine even better though. Would you share some more info on it( what kind of torch ,power usage, gas/air consumption...)What make and modle is it? so I can try to find a used one.
I have seen set ups made by the user were they make a template from thin plywood and then have a tracer pin that follows it manualy as they guide it around the work. I still like the idea of being able to proof the first one the walking away to do something else whil the machine continues to make parts.
   - merl - Monday, 08/03/09 00:51:07 EDT

As Dave notes a commercial burning operation can be a huge space eater. At the boiler shop, we had a MG systems burning table. Had 3 oxy/fuel torches and a plasma burner head, all on one gantry. Also had a solnoid prick punch for layout of secondary operations. Had a double table, so one table could be loaded while the other was burning. It would hold 6 full sheets per table. Since the plasma would burn 3000 inches per minute in thin stainless, we needed all that capacity to keep the burner cutting, and our shops supplied. Took more space than many small factories, and was served by a 20 ton or so bridge crane.
We used the thin stainless for lining the boiler walls, and building ice making equipment.
   ptree - Monday, 08/03/09 06:47:46 EDT

I am trying to install a point in a new log peavey.Can you instruct me on the proper steps to follow,thanks.
   Danny - Monday, 08/03/09 07:22:23 EDT

Our latest meeting was at a Pro's shop, he does major high end work. During the slide show he mentioned one job where he and a welding fab shop were the only bidders. The customer didn't care which one got the job. He got it even though his bid was $5000 *higher* because he was bonded and the other guy wasn't!

He mentioned that, especially now days, he has to be able to get a design and estimate out *FAST*; or not be considered for a job.

Thomas who got to play on a 500# chambersburg with some 2.5" sq stock and camped between a 1000# and a 2000# chambersburg!
   Thomas P - Monday, 08/03/09 12:17:36 EDT

John; You would not want a charcoal store *anywhere* where sparks could drop onto it as charcoal will happily start burning at the least excuse. If it was used as a store it would indicate a very "fire tight" floor to the forge was used.

   Thomas P - Monday, 08/03/09 12:21:12 EDT

Steven; please send me an e-mail as I might have a possible lead for you as to work.

   Thomas P - Monday, 08/03/09 12:21:55 EDT

I think my problems with CAD are multiple-
First, I am a mac guy. I have a PC in the other room, and my mac can boot windows XP native, but windows is so slow, so clunky, and so buggy that I seldom use it.
As an artist, I just prefer to draw, thats all- so when I need stuff cut by outside vendors, I let them do the CAD work.
But more than that- I do VERY complicated work. One project was 25 lifesize human figures, cut from 3/8" stainless, by waterjet. Each had hundreds of lines within the figure, making up all the details of clothing and figure.

Autocad munched these very badly- its simple enough to say, raster to vector means converting it to a series of points, connected by lines- but the unfortunate fact is, it was designed by engineers making simple geometric shapes, and it does a TERRIBLE job on complicated, changing radius, changing direction curves. Somebody, either me or the waterjet company, has to go in and add lots of points, move points, and correct errors.

Then, compounding that, most cutting systems dont actually use Autocad- they usually have system proprietary translation programs that often munch the lines AGAIN- the cutting shops dont mention to you that they, if they are good, check each program, and correct, before actually cutting.

Most of this is moot if all you want is circles or squares- which I never do. I cut things like persian rug patterns, with 400 unique oddball shapes in a 4' x 8' shape, or large portraits of Miles Davis, or lengthy text in typestyles I have handdrawn myself- all guaranteed to drive autocad, and its operators, into digital psychosis.

As for optical trace machines- there are lots of nice small ones out there, cheap used. Mine was originally 4'x4', I later enlarged it to 4' x 8'. It takes up 8' x 8', then, because it must have a full size paper pattern, as well as the cutting table. Not too large, given what it can do.
You can get them in either plasma or oxy-fuel, or both. Mine is plasma only, any brand of plasma cutter can be hooked up to it, although most people use the big 2- Thermal Dynamics or Hypertherm.
Good names in optical trace machines include the aforementioned MG, Koike, Esab or Linde, and my machine, which is a C&G.
You really need auto torch height adjustment on one of these, but that is available aftermarket as a separate module- it monitors the plasma cutting voltage, and runs the torch up and down to compensate for warpage and heat movement.
   - Ries - Monday, 08/03/09 12:46:12 EDT

Hi All,
It has been a while since I posted. I worked in a machine shop while I was in college and I would like to make knives in my spare time. I have had a few lessons on forging but I think I will start off using the stock removal process. Could some one give me some recommendations on equipment to buy. My budget is $250 per piece. I need a ban saw, a multi position belt grinder, a polisher, a heat treat furnace( or directions on how to make one), and I think I should get a table lathe and mill. Whatever you can recommend would be greatly appreciated.
   Mike - Monday, 08/03/09 13:28:12 EDT

CAD vs. Pencil: Ries, I agree 100% with you on the complexity of CAD and other computer drawing programs. They ARE slow, have a serious learning curve, AND as I have noted, I don't think ANYONE properly teaches the basic ground rules for using CAD systems. The result is it is an EXPENSIVE way to draw. It is also difficult to learn to create expressive artistic drawings with. It can be done but it is difficult.

As a machine designer I worked primarily with pencil on grid mylar (20 years). The advantage of mylar over the old velum tracing paper is that you could erase MANY times, make corrections and there was not a HINT on the print. The down side is that the wax pencils do not trace on tracers (I was told) and neither do prints. So to have a tracer follow a print we had to trace IT with a soft #2 pencil. Still the mylar had huge advantages.

CAD has similar and superior advantages for drawing maintenance. Not only do changes not show, you can keep multiple versions (revisions) and every print is a NEW original. Being able to make changes and KEEP the original version is a great advantage in the machine business.

The down side is CAD, even when expert is amazingly SLOW and thus expensive. It is why draftsmen are still being paid pitiful wages even though it is now a high tech field.

AutoCAD, while an industry standard is the PITS for drawing. There are numerous much simpler CAD programs including several for the MAC that are much easier to use and work better than AutoCAD. AND they all produce DXF files better than AutoCAD.

My old DesignCAD, which was previously, ProDesign originally used a cubic spline to define curves rather than the Bezier curve which AutoCAD and most drawing programs use. A cubic spline is based on matrix math and is a bear to program unless you are brilliant in math. But the use of the result is vastly superior to the Bezier.

To define a curve all a cubic spline needs is 3 or more points. To edit the curve all you need to do is move any ONE point. The fewer points you use the more graceful the curve. To trace an image you just set a minimal number of points on the line and POOF you have your curve. To edit a Bezier you use vector handles that are OFF the line somewhere in space. You change the origin thus the angle and the length thus the "force" of the vector to edit a curve. This is a PITA and non-intuitive. A cubic spline is easy and intuitive, the perfect CAD curve tool.

AutoCAD now supports splines but not well and still uses a Bezier as their "preferred" curve.

The advantage of your tracer is you can make a drawing in about 5-10 seconds of a simple shape and be cutting it NOW. It would take me a few minutes more to make that drawing and then an hour to convert and send to be cut. HOWEVER, I can scale my template up and down, change its proportions (stretch/compress/warp) in seconds. AND I can store thousands on a floppy disk, email them to others and make PDF's if necessary. IF it is something too big to work on MY machine (if I had one) then I could send it out to others. . .

I too am a pencil guy working in a CAD world. . .
Everything has its pros and cons.

Remember, I'm the guy that keep reminding folks that they often miss the ART in Artist-Blacksmith.
   - guru - Monday, 08/03/09 13:33:09 EDT

Mike's Needs: Mike, Are you saying your budget is limited to $250 per machine? You had better plan on building them ALL or spending a lifetime chasing around auctions. Good motors alone for some of this machinery will cost $250 a piece. To start see:

50 dollar knife shopWayne Goddard's $50 Knife Shop
By Wayne Goddard
Making cable Damascus, budget blade making equipment, tribal knifemaking.
Reviewed by Charley Pierce and Jock Dempsey

Then do some research WAY back to the 1970's. Mother Earth News had some articles on building a band saw using auto wheels and tires for the saw wheels (works great). Narrow tires such as the old VW 15" tires were prefered but any will work. Frames can be wood or metal but for metal cutting the table should be metal and you need a good guide system.

Good lathes and mills are currently pretty cheap but you are going to need to spend $1500 to $2000 each with attachments. In the used market that will get you very nice small commercial machines but that is infinitely better than the toy miniature machines for the same money. While you can build your own I do not recommend it.
   - guru - Monday, 08/03/09 13:52:55 EDT

I had seen a small vertical/horizontal ban saw for around $250 on a year ago. I forgot most of the details about it that is why I was asking if any one knew of a saw like that. Obviously it is not heavy duty but I thought it would be good for knife patterns. I also thought there were belt sanders and polishers for around $250 each. I was not thinking of buying a full size lathe or mill. I have seen small table ones pretty cheap. Any ideas on how to put together a heat treat furnace? I was thinking of modifying a pottery kiln. Thanks for the book recommendation and any others ideas you have.
   Mike - Monday, 08/03/09 14:56:48 EDT

Thanks Ries, you answerd a couple of my next questions too,
about how the machine knows ware the work higth is.
That is one thing that got me realy interested in the PlasmaCAM was that you could scan a drawing in to the computer and it would translate that into a DXF file for the cnc control. I don't know how smoothly everything is supposed to work (everything works perfectly in the sales video...)but, I can still see the high potential for de-bugging a dxf file to make the part work.
With the optical tracer, does it run in real time or does it "read" the drawing, save it, and then run it as fast as the torch will cut?
Of corse I'm always curious if these machines with the quazi Z axis motion will accept a Fordum hand piece or some kind of Dremal like tool for doing flat engraving or cutting out stuff from non-metalic material?
I too am a pencil and paper guy. As a matter of fact I just picked up another 4'x6' drawing table with a good top and it came with two pantogragh arm machines and several differant sets of scales for same, plus all of the guys technical pens and pencils and some various triangles and such, FREE for the hauling.
I made my first drawing table from a huge desk top someone was going to throw away and I use it all the time, far more than I use the cad programs I have.
I was going to mention however, that I have seen large sketch pads on computers for the pupose of free hand drawing. Likely quite expensive I would guess.
I will always prefer the experiance of making a hand drawing to the struggle of doing one in cad.
   - merl - Monday, 08/03/09 15:08:37 EDT

Merl, Touch pads and CAD. . please read my posts above about CAD issues.
   - guru - Monday, 08/03/09 16:24:43 EDT

I use mylar sometimes, but I am a 1000H man, mostly.

PlasmaCAM say in their advertising that some of their customers have mounted routers for engraving on their machines. So it is possible.

The simplest optical trace machines have NO computer. So, no memory. They trace a drawing. I draw mine with a sharpie pen on white 48" paper. A roll of it lasts me years. You can then use white-out, and change parts you dont like.
Its 100% Analog.
   - Ries - Monday, 08/03/09 16:48:24 EDT

Small Saws: The typical cheap imported 4x6 saw will do a fair amount of cutoff work but they are basically a straight line machine. The vertical use is very limited due to cheap guides and the ability to use only ONE blade width. They all run 0.025" x 1/2" blades. Curve cutting requires narrower blades which these saws do not accept. While they WILL cut a slight curve it is hard on the machine and the guides will fail in short order. To use a range of blade widths a band saw must have rubber tires. Cutoff saws that twist the blade as these do have cast iron wheels with a shoulder that the back of the blade must run against.

The reason the MEN band saw used auto wheels and tires was the TIRES. Band saws use a rubber tire so that the blade teeth have somewhere to go. They compress into the rubber. This lets you use blades from 1/8" wide to 1.5" on the same saw. The curved surface of the tire is also natural crown so that the blade tracks in the center of the wheel.

Cheap grinders: Lowes carries a cheap mostly plastic belt sander that might last through one belt. . . I see almost new ones in bad condition in flea markets for $50 and that's $50 too much. . . Decent ones start at just over $1000. You can $250 on a good contact wheel. . .

Ray Clontz Belt Grinder
The above is photos with enough detail to build a nice durable grinder. The purpose of the old drive shaft and U-joint is to make a needle bearing pivot so that the belt tensioning arm is very steady.

If you have a welder and a lathe to make some of the parts fit you could build this grinder for around $250 if you scrounge and purchase the cheapest motor and bearings you can find. If you have to buy all your parts and pay for a good quality motor it will run $500.

But if you want CHEAP then the Wayne Goddard route with wood parts is the way to go.

Here is a video of a very nicely build professional duty grinder.


The caveat here is this fellow has access to a lathe with at least a 12" swing and a milling machine to make many of the snug fits. This is NOT a cheap machine to build but I suspect he has 20% or less than what a commercial model like it would cost.

If you are going to do stock removal then the grinders are EVERYTHING.
   - guru - Monday, 08/03/09 17:20:42 EDT

For a inexpensive belt grinder look at a Kalamazo 2 x 48..it's a small but heavy duty industrial machine that has been manufactured forever..and can often be found on Ebay for under $200...For a bandsaw get a Milwaukee or smilar portable and mount it on a base..many Knifemaker [me included]use these..If you don't want to convert it yourself theres a guy on ebay that sells a kit...forget the lathe and mill for now,you don't need them....To heat treat you can use a torch and temper in a toaster oven...for a Great inexpensive forge try "Uncle Al,the Knifemakers Pal" at Riverside Machine..his forges are used at the ABS school...their simple, effective and bulletproof..Beware of buffing machines..They are much more dangerous then they look..Good Luck,,,,just remember knifemaking is highly addictive!
   - arthur - Monday, 08/03/09 17:48:34 EDT

Belt Grinder:
This is about as simple as it gets, made for under $250, including the drill bit and 1/2-20 tap. Hitting that price requires some scounging of steel or design flexibility based on what your steel supply house has in short drops. This is made with 1/2"x3" plate pieces, 1"x2" bar, and 1/2 round, and a welder. You can substitute whatever steel you find within reason, but I assure you that the WEIGHT helps reduce vibration, so I'd advise against hollow tube. Based on what you find, the size and shape of the belt's triangle may vary, so I didn't bother with precise measurements. You can figure our the exact sizes by laying out the belt and wheels. A spring loaded tension wheel takes up any slack.

I've built several of these for my own shop, as its easier to build a differnt shape than make one which is overly configurable.

Based on your scournging, a nice upgrade would be cone pulleys for adjustable speed.
   Mike/Marco - Monday, 08/03/09 18:25:29 EDT

I also looked at the Kalamazoo belt grinder, BUT let me tell you the very best belt grinder for the buck. It is a Grizzly 2 x 72 belt grinder, it comes withb a 4
   - Mike T. - Monday, 08/03/09 18:45:49 EDT

For a quality 2 x 72 belt grinder, look no further ! Grizzly makes a high quality grinder at an affordable price. As a matter of fact they design and build low cost QUALITY tools so the average man on the steet can buy them.
To look at the grinder, go to Northcoastknives.com
   Mike T. - Monday, 08/03/09 18:49:35 EDT

Would you sell me a set of plans for your belt grinder ? E-mail me and I will send you some $$. I looked at McMaster-Carr's pulleys and it looks like they carry everything for it.
mike t.
   Mike T. - Monday, 08/03/09 18:54:10 EDT

Mike T. - no $ necessary, if you can wait a day or two, I'll add measurements to that drawing. Remember, your measurements may vary based on what steel you can get cheapest. I used those sizes because that's what my steel supplier had in a short drop bin.

This is the sort of frankengrinder type monster which requires more creativity than "plan." As the Guru says often about the various Junkyard Hammers, you work with what you can find. If I produce an exact parts list, you may find this costs you more than a commercial model.

The motor cost me $80 at harbor frieght some years ago
The wheels totalled about $100 with the bearings installed
The steel was < $20
The Drill and tap about $20
Three 1/2 bolts < $10

If you have to pay more for any part, you're over $250. Of course, you get a much heavier and stiffer machine than a grizzely G1015.

The ESSENTIAL part is that you have RIGHT ANGLE joints and drill/tap the holes for the front wheels PARALLEL! You can shim the engine mount with cuttings from a pop can and washers, but those front wheels MUST be parallel, you you have no hope of keeping a belt on.

Before you attemp this, consider your capabilities.
Can you weld?
Can you cut right angles?
Can you drill/tap parallel holes?
   Mike/Marco - Monday, 08/03/09 21:42:36 EDT

True (square) holes. . . takes a drill press to do right. Even a hand crank one.

Paw-Paw had a belt grinder that someone had made the major parts for and he was to put it all together. Some sloppy hole drilling, a little misalignment and bad part substitution and it was junk. Couldn't keep belts on and couldn't keep it from shaking apart. We put it in the auction and it sold for less than the motor cost. . .

One problem folks have is wheels that run out. Not all are as true as they need to be and even identical purchased wheels will run good and bad. Wheels can be trued easily if you have a lathe and it can be done in a drill press but not quite as easily. I trued the tires in my band saw using a scraper and a sanding block while it was running. It made the difference between an 800 pound machine that would walk across the floor from vibration and one that was quiet and rock steady.

Larger wheels also need to be balanced in some occasions. The video I linked to above had a number of large wheels in it. They had all been lightened as much as possible. Lightening the weight by machining often cures imbalance problems.

So the ability to build one of these is a matter of skill and judgment. But so is maintaining one. Contact wheels go bad and identical replacements may not be available, bearings in proprietary wheels fail and are hard to find. . .

The thing that cost the most in many of these projects is the motor. If you can scrounge a good one (or many) it really helps. Sometimes they come easy, sometimes not. I bought a half dozen fractional HP motors from a fellow without studying them closely. . . While they were all single phase they were also all 220/240 OR 440. They were also fan motors that relied on the fan they were driving for cooling. It was a bad deal on my part. But I've also come across new Baldors cheap. I have a number of new 3PH (1HP I think) motors I could make a good deal on.

AND I have two motors sitting in the shop that need new bearings and a good cleaning. They were in a flood and the bearings have locked up. They were not connected so there is little chance of electrical problems and its been years since they were wet.

Back when I was in super scrounging mode I came up with a bunch of old motors. Some were good, some bad. Several being identical were made into one and parts from another repaired the motor on my small lathe. On one I turned the scored shafts down to .010" under and made custom bushings and a custom pulley. Lots you can do when you have time and no money and a few tools.

I found a grinder similar to Marco's that was made with nice aluminium part that were all gold anodized. . . Over $1000 for a simple small belt grinder. Scrounge the right parts, good steel and you might do as well.
   - guru - Monday, 08/03/09 22:23:24 EDT

You know how I like to argue, Guru. Well you got me to wondering, and you can think on this too, In a machine where we are shooting for a certain surface speed (or rim speed) DOES a large wheel need more thought to balancing? The larger wheel will be turning much slower. So, I don't know, but I thought this might keep you awake tonight.
   - grant - Tuesday, 08/04/09 00:23:03 EDT


Yes, I have equipment to build with. I appreciate you going to the trouble of drawing plans for the grinder.
   Mike T. - Tuesday, 08/04/09 02:28:17 EDT

Frank, I thought the best way to answer your question was to draw a plan – see http://www.flickr.com/photos/40413182@N02/3787309757/in/set-72157621890877906/. I take your point that the fire pit seems to sit low – unless the fire was raised, any metal would be diagonally placed downward into the fire. As you’ve probably gathered I am not a blacksmith, but I can see that the set up wouldn’t make working with long metal very easy! Is it possible that it was a smelting shop instead of a forge for example used to make lead shot for guns? The inset at the rear of the forge might have been to support a spindle of some kind, the other end sitting on the front top rectangular slab??
The shelf below the front top rectangular slab is at the same level as the fire pit. It is blocked off from the fire pit by fire bricks. Is it possible that this might have been open at some time? Or could it have been a store for wood kindling as per Guru’s forge picture? (Guru, I take your point about debris, thanks :).
I think you are right about the broken edge at the back – I intend to fill that in. Re the gaps in the stone slabs, the stones do look as if they were placed deliberately to leave gaps. I was beginning to think that the fire pit was lined with lime mortar – thus sealing the pit. But if the gaps were for air flow, then the fire pit couldn’t be sealed. If this is the case, what have they used? Could the substance in the picture attached to the molten metal be old, dried, sand? How does sand go after substantial heat and time? It has been mentioned on this forum that clay was used. But, again, wouldn’t that seal the pit? Does anyone know whether a side draft forge requires an air flow up through the fire, or not?
If the fire pit wasn’t sealed then, Thomas, you are probably right that the bottom cavity was not a charcoal store. Maybe back to Bruce’s other thought – a place to store hot metal.
Thanks everyone for your thoughts. Back now to “crepe” ing the forge walls!
   John - Tuesday, 08/04/09 02:41:25 EDT

Several thoughts have crossed my mind reading the Napoleonic forge thread over the last few days.

* How any traditional forge was built may not have been the most efficient way to build a forge - sometimes tradition or local custom or the whim of the builder may trump actual efficiency.

* Old forges may have been built and rebuilt according to needs and circumstances and the work patterns of the individual smith. The forge may be adapted to the smith, or the smith adapts to the forge.

* Accidental advantages of odd features of the forge, as it exists now, may or may not have existed when in full operation. The cavity in the back wall under the chimney hood may have been useful for suspending longer stock in the heart of the fire; or may have housed a small coffee pot, or it may have had some structure mortised into it; or may have been for another purpose altogether. The supporting stone slab(s) at the bottom are really low; I suspect that they just held an upper bed of lime cement, then dirt and ashes and accumulated slag and scale and whatnot up to a reasonable level somewhere near the bellow's tuyere (which may have been originally located elsewhere in the shield wall, it looks a little too far forward; but see the first point, above). I suspect that the slot at the bottom would have been covered with cement or plugged with debris, and probably served no purpose. It's just how the two slabs met in the middle, to be plastered-over with cement.

* The box of farm tools is interesting: hinge pintles, garden forks, latch hooks, adze… All of which could have been made in the forge, or were there to be recycled in the forge into something else. It looks a lot like a box that I found on our farm (existing structures from the 1830s, but some colonial finds) except our farm never had a smithy (to my knowledge…until I built one) so it also looks like the usual agricultural clutter of tools awaiting new handles and other mathoms- too junky to use, too potentially useful to throw away.

* Casting was certainly done in small forges, and brazing too; but the set-up of this forge does not lend itself to heating crucibles, which in both bottom and side blast forges is not as straight-forward as you would think (and sometimes very fuel intensive). Big green deposition of copper alloy debris would point to casting as a major operation; but otherwise, it's just another tool in the smith's arsenal of metalworking techniques.

Side-blast forges and charcoal fuel tend to burn, when at rest, with much greater enthusiasm than (in order) soft coal, coke and anthracite. In truth, banking the fire is more important to conserve fuel rather than to keep the fire going.

Finally, is there anybody in the village that remembers the forge in use within living memory? There's always something needing fixing on the farm; and a forge is a useful tool for general repairs. Sometimes someone will come in and say: "Oh yes, that's what the smith used for this; and that's where he kept his bottle of brandy!"

Your pictures have been invaluable; this has been fascinating. Have you looked at the Diderot illustrations on the net or in the library yet? Are you going to just restore it, or restore it to working order and use it? (If you plan to use it, the roof and chimney work may be a little tricky. How high did the original chimney extend above the roof ridge?)

So, there are my thoughts, reality may vary.

Frank, Thomas, Alan, Jock (et al)?
   Bruce Blackistone (Atli) - Tuesday, 08/04/09 08:31:10 EDT

Forge Furnace Purpose: John, There is always the possibility that the furnace was for a small crucible melting operation of anything other than iron. Jewelers, pot makers and various metal workers melted and cast their initial product. The fire pit would need to be deeper for this purpose if the crucibles were very large. However, in that case there should be some evidence of a small foundry operation. Old broken clay crucibles (may appear to be pottery with metal/slag stuck to it), foundry sand (which may be hard to identify), wooden casks or mold (mould) boxes.

One of the best ways to determine the use of such a place is soil analysis looking for heavy metals. Lead, copper, tin, silver and gold are very persistent.

One of the things I thought curious was that the forge chimney is a seperate construction from the stone wall, they are not keyed together and made of different materials. This indicates to me that the building was built for some other purpose and converted to a forge latter.

I think the problem is that a lot of weathering has gone on and that the site has been disturbed. Farmers or gardeners needing bricks or rocks, children building castles out of forges. Or just someone picking up and replacing displaced stones that may have been a trip hazzard.

Weathering can make a big difference. As we have noted many old forges had soil fill and clay that could wash out. And I rarely see old buildings that have been abandoned to the point of the roof collapsing that plant life has not taken hold and done a lot of damage as well.

On a site like this there needs to be a lot of research into the history of the property.

"Side Draft" Technically this is "side blown" and what happens is the blast makes a very hot fire a limited distance from the tuyere. The blast (which is often just a gentle breeze) is then turned upward by the rising heat. As long as there is oxygen left in the moving gases there will be fire. In some forges there is a bowl shaped depression formed in the fill and the blast comes in at the side near the bottom of the bowl or "fire pot". In this case the bowl turns the blast upward. In either case, the air comes in from the side and goes UP.

   - guru - Tuesday, 08/04/09 08:54:46 EDT

Balance: The large the part the more important balance is. The faster a part rotates the more important balance is. Parts machined (turned) all over or made from solid are less likely to be out of balance than cast or fabricated parts. The lighter the part the less material there is to create imbalance. . .

The surface speed of my band saw is over 5,000 FPM (+60 MPH) with 20" wheels. In this case balance is not just the misplaced weight on the wheel but the blade shaking side to side if the wheel is out of round. Removing just a slight hump from the rubber tires made a big difference.
   - guru - Tuesday, 08/04/09 09:05:01 EDT

Belts... I would LOVE to get a Bader, any type.

Q: A while back there was discussion on twisting bars. We all agreed that the effect of twisting a single bar does NOT reduce its' length. But twisting multiple bars DOES. I know this is due to the linear something or other, mating surfaces blah blah. But is there any formula for estimating this length loss? i.e. two 1/4" rounds twisted over 5" will shorten to X. More bars mean more loss? Bar diameter? I know the formulae for drawing out and the resulting additonal length, just didn't know if there was one for twisting.
   - Nippulini - Tuesday, 08/04/09 09:11:06 EDT

Dynamic balance in a rotating object:
I can't give you the exact formula off the top of my head but, obviously the relationship between diameter and surface speed are critical to each other.
A balance spec for a precision roller is usualy given as "X" oz.@ the required surface footage of the roller for a dynamic spec.
For a static spec it is just within "X" oz. at whatever diameter.
Whatever you're building should either be machined inside and out for balance or at least staticly balanced to zero rotation.
How large is this wheel and how slow is it turning? if I may ask...
   - merl - Tuesday, 08/04/09 09:14:22 EDT

Side draft...; side blown...; "side blast!" - that's the term I was looking for!

Post-habitation destruction... At least they don't have groundhogs in France; and I imagine any rabbits end up in the stewpot. ;-) Nothing like a groundhog for displacing huge amounts of archeological material and muddying the stratigraphy!
   Bruce Blackistone (Atli) - Tuesday, 08/04/09 10:00:44 EDT

Hmmmm. . . Hedgehogs?

Spirals: To calculate the length of a piece twisted arouund another.

Take the part center line diameter (core width + 1/2 wrapped part) times PI (thus the circumference of the circle) as the base of a right triangle.

Then take the length of one 180° turn or twist in the core stock as height of the triangle.

The length of the spiraled part is then the hypotenuse of the triangle. SQRT (Base² + Height²)

The amount of additional material (OR stretch) is the difference between the hypotenuse and the height of the triangle.

Many metals stretch a great deal. The fact that a square bar is twisted indicates the ability of the steel at the corners to stretch as much as needed
   - guru - Tuesday, 08/04/09 11:12:06 EDT

I have a question about forge welding. recently I was working on a hewing axe, and I could not weld it, I gave up on it after an hour of trying. Exactly after I started another axe, and it welded fine. I use mild steel used for welding, that you can buy at any welding supply some of it weld and other do not. If any answers to why this happens I would greatly appreciate it.
   Matthew Bledsoe - Tuesday, 08/04/09 11:24:13 EDT

Matthew, "Mild Steel" is actually a pretty broad range of product. It comes in a variety of chemistries from SAE 1008 and 1018/20 to structural A36 and others. Its form can be hot or cold worked. Some is oiled, some plated with zinc (galvanizing) and some just scale or rust. All these can effect weldability in the forge.
   - guru - Tuesday, 08/04/09 13:14:47 EDT

On John's old forge:

I think Bruce covered much of what I could add.

As for the forge chimney not being a part of the walls, that could indicate the building was not originally a smithy or it could simply indicate the forge didn't always have a chimney. I have seen a few old smithies in which there was no chimney, just a smoke hole in the roof.

In order to get the most out of my (and Bruce's) archaeological opinions, you really need to invite us (and Jock and Thomas too) over to look at the situation, all expenses paid, of course. (grin!)

All kidding aside, there are some things that simply can't be identified through a small photo. The stuff you say looks like melted metal on lime mortar is difficult for me to see clearly, but I doubt that's what it is. It could be heavily rusted iron on mortar, I've certainly seen that before in humid locations.

It's one of the sad truths of archaeological research of forges that most of the useful stuff in plain sight tends to go away very quickly, leaving little to reconstruct.
   Alan-L - Tuesday, 08/04/09 13:35:17 EDT

I think you may have misunderstood my question. I'm talking about groups of rod twisted, not one twisted around another. I've made a jig for simple hilts on the stainless sword swallower project. The end result is a U shape that elongates at the tip of eah end and is perpendicularly outward (tips scrolled). At this stage the hilt is 4 inches. Heat and twist the U and now it's down to 3 inches. Then I hammer the twist flat. Now if I took 4 inches of square rod and twisted the same amount, there would be no reduction. If I used three or four rods, the reduction would be less or more? I think you thought I meant scrolling, I mean twisting.
   - Nippulini - Tuesday, 08/04/09 14:50:22 EDT

No, I understood twisting. A jewelers' technique is to take say a square bar and two or four pairs of twisted wire bundled on the flats of the square and then twist the whole assembly.

twisted silver wires in bundleAn Interesting Twist

We can pickup useful things from people in other disciplines. This twist is in silver but could be made in brass or steel (or a mixture of both).

At left there are 4 pieces. Two are lengths of pretwisted wire. The others are a square bar and plain wire. All three were welded together at the ends and then twisted as a group.

anvilfire NEWS, May 2002 Edition, Camp Fenby
   - guru - Tuesday, 08/04/09 15:49:13 EDT

I would think that one factor in your proposed equation would be the number of twists per inch as well as size of stock and length twisted.

Forge welding: some mild steel seems to resist welding, (especially cold rolled) removing the surface layer with a grinder before attempting to weld may help. The big Box hardware store's "weldable steel" means that it should be able to bw arc welded but does not cover forge welding at all!

   Thomas P - Tuesday, 08/04/09 17:17:57 EDT

Just to answer Grant's question directly, the formula for centripetal acceleration is M*V^2/R. If the surface speed is constant, so is V^2, and the accelaration of a mass on the circumference of a wheel would *decrease* as the wheel gets larger. If you assume a given extra mass on the circumference of the wheel, doubling the diameter should cut the acceleration (and the associated force) in half.

On the other hand, doubling the diameter of a wheel would normally increase its mass by 4 to 8 times (depending on whether the wheel thickness stays constant or increases proportionally with the diameter). So if you assume a wheel is out of balance by, say, 1% of its mass, doubling the diameter would increase the out-of-balance mass by 4 to 8 times and the resulting force by 2 to 4 times.

Of course, if you keep the RPM constant and not the surface speed, doubling the wheel diameter is just plain scary.
   Mike BR - Tuesday, 08/04/09 18:28:15 EDT

John, Thanks for the drawing. I'm still cogitatin'.
   Frank Turley - Tuesday, 08/04/09 19:11:52 EDT

Not to forget the moment arm effect of larger wheels as well.

   Thomas P - Tuesday, 08/04/09 19:57:17 EDT

Meri & Mike: I just knew it would keep someone awake!
   - grant - Tuesday, 08/04/09 21:19:30 EDT

Nip, Twisting 2 wires is like wrapping a wire around a "rod" with a diameter of 0.0000. The neutral plane is 1/2 the wire's diameter.

When You twist multiple wires there will be some space in the center, as if You had wound them around a small rod. The neutral plane will now be located at the distance from the center of the bundle [center of this therotecal rod] plus 1/2 the wire's diameter.

This will make a larger bundle become shorter than a pair or smaller bundle when twisted an equal ammount.
   - Dave Boyer - Tuesday, 08/04/09 22:21:53 EDT

Belt Grinder:

Wheel true, balance, and runout are things I feared, which is why I spend the largest part of the cost on GOOD wheels. You can scrounge everything else, but less than perfect wiheels will either shred expensive belts, or worse. What's worse? My first grinder LAUNCHED a belt at me like a rubberband gun, but with the belt still turning. A 24 grit road rash just about removed my beard on one side, and destroyed the right lense of my safety glasses.

Sunray-inc.com makes extremely well balanced, true wheels witha steel or aluminum core and differnet hardness/color plastic surfaces. The grinder I use most has one 70A and one 90A durometer wheel, and they seems to hold up the same under heavy grinding.

Beaumontmetalworks.com [conviently not 5 miles from my house] makes very high end grinders, machining all their own parts fon big CnC lathes and such. His drive wheel was great, but the idlers wore funny under heavy grinding [8+ hours a day] where the Sunray ones don't. The 4" drive wheel is a great deal, though, and lowers the SFPM of my grinder significantly from the 10" wheel on the "Square-Wheel" grinder which was my inspiration. Seriously, look at Beaumont's KGM grinder... if I had $2K, I'd get a full set up from him. I got to use one a little in his shop, and its a sweet machine.

I HIGHLY recommend buying the same wheels I did, as I couldn't find them cheaper AND better.

It'll be a week before I can change that drawing, but here are the important sizes:
The red legs are 12" each, but that makes a VERY tall machine. Mine stands in a large rubbermaid tub full of water to the lower wheel, but with the engine above water. You could have much smaller legs depending on the height you want.
There's abotu 24" of 1/2x3" bar
The big green 1x2" beam is 22" long. You need another 8" for the platen.
With the wheels on 9" centers, and one end of that beam on that center line, taht gives me about 26" from the center of each idler to the center of the drive wheel. This is where YOU have to engineer things depending on your available parts.

Here's the order I build this. Dress all edges, bevel all wekds, etc... use good machine shop discipline as explained here often by better men than I.
1. Grinder head: cut 1/2x3" plate, 11" long
2. Drill and tap two 1/2-20 holes, 9" center to center, 1" center to edge as shown [blue plate with wheels.
3. Mount idler wheeps with 3" hex bolts 1/2-20. I use larger nylon washers over the bearing surfaces.
4. Check wheels for alignment.
5. Cut 1x2" bar pieces, 5" long and 3" long
6. Lay 5" piece wide face [2"] down. Center 3" piece on top, narrow side [1"] down, aligned on one long edge. Weld.
7. Stand wheel plate, wheels down, on a flat reference surface. Fit platen between wheels, 5" flat side down. Clamp and weld. This aligns your platen to the belt line.

Motor Mount/Arm
8. Cut 3x3 right triangle off remaining 1/2x3 [blue] bar.
9. Stand 1x2" [green] bar on end, align triangle to wide face at end and weld. This gives you support for your engine plate.
10. On remaining 1/2x3 [blue] plate, mark and drill holes for motor mounting, allowing 2-3" of shaft to extend beyond plate edge. Cut off excell plate at other side of motor foot.
11. Stand Long arm/trangle on motor plate, aligning edges. Check for square. True as necessary and weld.
12. Cut and weld 1/2 round [red] legs to the arm/motor plate as pictured.
13. Mount motor and drive wheel

Assembly and alignment
14. Clamp Grinder head to arm roughly where pictured
15. Move motor as necessary and ship to align drive wheel with idler wheels
16. Fit a NEW belt over all three wheels
17. Loosen clamp and slide grinder head forward until belt is tight, then BACK so its loose enough to run a pencil between the belt and drive wheel. Clamp
18. repeat #15
19. Weld griner head to arm.

Tomorrow I'll write out the steps for the tension arm.

   Mike/Marco - Tuesday, 08/04/09 22:29:43 EDT

I recant, Sunray-inc.com also has drive wheels, significantly less expensive than Beaumont. I'd opt for a 4" dia, 3" wide drive wheel in a softer surface than your idler wheels.

Drive wheel for the next grinder, a 2 wheel vertical job with a long platen on one side and a long slack on the other, is definitely coming from them, along with the big 8" wheel.
   Mike/Marco - Tuesday, 08/04/09 22:43:34 EDT

Okay, I get it now. Thanks, I had to wrap that one around my brain for a minute.
   - Nippulini - Tuesday, 08/04/09 23:29:01 EDT

Twisted bars. . Note that I used ONE twist length so twists per inch are not needed. You can start there if you want. .
   - guru - Tuesday, 08/04/09 23:48:36 EDT


An 8-10 inch contact wheel is needed for hollow grinds on knives, 10 inch preferably. The Grizzly contact wheel is only 4 inches, but the 10 inch can be purchased for 64 bucks.
   Mike T. - Wednesday, 08/05/09 04:17:13 EDT

Also Marco,

It is very good of you to go to this trouble, I think many people can benefit from your plans.
   Mike T. - Wednesday, 08/05/09 04:20:14 EDT

Maybe Guru and Marco can get together and post Marco's plans and pictures on Anvilfire. I think he has a bead on things.
   Mike T. - Wednesday, 08/05/09 04:21:53 EDT


I had an Uncle from Yugoslavia, his name was Marco Radich, but we called him Uncle Mike. Does your ancestery go in that direction ? Just curious...:)
   Mike T. - Wednesday, 08/05/09 05:07:43 EDT

I live in Cape Town South Africa and am not a blacksmith but a woodworker. I make, amongst other things, rustic wooden chests but am unable to get hand forged hardware for my chests (hinges, handles etc). I have come to the conclusion that I should make my own hardware but need to know if there is any literature specialising in this field of blacksmithing. I have a couple of books on general blacksmithing and also have a small anvil and a few rudementary tools. I would appreciate any info/advice you could supply.
Kind regards
Geoff Hudson
   Geoff - Wednesday, 08/05/09 08:40:53 EDT

My research on an article I'm writing on damascus steel has turned up a method of producing the material called 'zipped up welding'. Has anyone ever heard of this technique for making damascus billets?
   coondogger - Wednesday, 08/05/09 09:37:38 EDT

Geoff, There are quite a few blacksmiths in ZA but you need to look for them. This would all be custom work.

The best books I know of on hardware of this type are about Old English and Early American hardware.

Early American Wrought Iron
Three Volumes in One by Albert H. Sonn.

Colonial Wrought Iron - The Sorber Collection
The new reference on Colonial American wrought iron hardware and other devices by Don Plummer, published by Skipjack Press.

Antique Iron

by Schiffer, Schiffer Publishing.

Iron and Brass Implements of the English House

Seymour Lindsay - This one may be out of print

The first two books above are reviewed here, the third is also in print, the fourth MAY be in reprint.
   - guru - Wednesday, 08/05/09 09:51:26 EDT

Zipped??? Coondogger, I never heard of "zipped up". In recent years most of the folks making laminated steels have gone to fluxless container methods where the billet is sealed (maybe zipped) into a stainless tube with a vent. A drop or two of kerosene is put in the container to burn up the residual oxygen and purge it out of the container. After welding the container is stripped off. Some are now using stainless foil to seal up the billet. This is much more flexible in use and comes off easier.

Due to the expense and one-time use of the container or foil these methods are used with many thin laminates rather than fewer thick ones. Starting with a pile of thin laminates reduces the total number of welds and thus increases the chances of successfully making a perfect billet with no flaws.
   - guru - Wednesday, 08/05/09 10:22:50 EDT

"Zipped up welding" may be a personal term as I can't seem to find it and have not heard of it before. Where did you run across it?

   Thomas P - Wednesday, 08/05/09 10:53:14 EDT

The only folks I know using containers are prople doing mosaics or other exotic Damascus...Most knifemakers still just stack and bend or stack cut and restack..For container welding I've always had luck using a square, thin walled tube, welding ends on and after putting in my steel,filling the voids with powered 1084,no vent ,no kerosene,no WD40,etc...just my .02
   - arthur - Wednesday, 08/05/09 11:14:52 EDT

Bruce / Guru / Alan,
I agree that the property history is key. We know that the forge was NOT built in 1785 – the French commissioned a plan of every village in the land, known as the Napoleonic Cadastre. The adjacent barns and houses (including ours) pre-date 1785. The French did not key into adjoining buildings or even corners of the same building. They relied upon the walls being about 20” thick to stay upright. They didn’t even have foundations – so many old buildings today have cracked walls or are leaning – but have probably been like that for 100 years or more! I think it may have been purpose built as a forge as there are large front and side windows besides the forge – this would give better ventilation in the summer heat and is unlike a normal barn construction (which have large doors and few, if any windows). Also, the inlet in the back wall suggests that it was there for a purpose – I don’t think it was coincidence that the forge was built around it. But, I may be wrong! The forge may not have had a chimney initially, but it is made of the same bricks that are in the chimney stack of our house (which pre-dates the forge), and which are very popular in this area. The fact that it wasn’t keyed in to the rear wall doesn’t surprise me. But it was well keyed in to the side walls of the forge so it wasn’t going anywhere! Bruce, in answer to your question the chimney needs to be circa 3m to clear the forge ridge tiles.
We know the owner of our property back to circa 1900 – no further, I’m afraid. There is a very old French lady in the village that may be able to help. Also, there is another long established family in the village who has the only other remaining forge and whose grandfather was a blacksmith. Unfortunately our French is not good so we will need a translator to speak to them!
The horizontal position of the tuyere is driven by the size of the bellows. The back wall stopped it being any closer to the back wall.
Our intention is to recreate a working, as near to the original forge that we can. A neighbour of ours is keen to get it working proper – he is very much into metal working but hasn’t got access to a forge. I will certainly fire it up with him at least once. However, in reality it will be a summer kitchen – sorry guys!!
Alan, airline tickets are in the post – TOMORROW.
   John - Wednesday, 08/05/09 11:20:51 EDT

What is the quality of vulcan anvils? Im looking at a 110 lbs vulcan anvil? Are they cast iron or cast steel or what? Thanks!!
   - Jacob Lockhart - Wednesday, 08/05/09 11:53:04 EDT

The guy I heard the expression from is Todd Kinniken of Eureka Forge in St. Louis. It is, as you described, a closed tube, fluxless welding for producing billets of pattern welded steel. Is there a more common name for this process?
   coondogger - Wednesday, 08/05/09 11:55:51 EDT

Mike T.

My real name is Mike, Marco is my name in the SCA [where I do most of my sales], a quasi living history-ish organization. More people know me as Marco than Mike. My ancestry dead ends in Poland on one side and ex-pat Italian butchers in France on the other... they make purfume, now.

Big wheel belt grinder - you could easily modify this plan to have one larger wheel rather than two. It would require you forming up the grinder head as above, but with the one large wheel instead of two and a platten, then fitting a belt to determine the final position.

If you LIKE drilling and tapping holes, you could bolt the grinding head ot the arm, and be able to trade grinding heads. I prefer to build separate machines.

   Mike/Marco - Wednesday, 08/05/09 12:51:13 EDT

Coondogger, container or enclosed. Container had been the common term but using foil is relatively new. Come up with the best or better term and everyone might start using it.

   - guru - Wednesday, 08/05/09 13:21:28 EDT

Vulcan anvils are made like Fisher-Norris anvils. Fisher inveted the process of welding the steel face to the cast iron body in the mold and is considered the best of this type. Vulcan comes second and then Star a distant third or forth.
   - guru - Wednesday, 08/05/09 13:25:53 EDT

Coondogger, the knifemakers I hang out with refer to that as a can weld or a cannister weld.

John, thanks! We'll see you soon. (grin!)
   Alan-L - Wednesday, 08/05/09 13:28:54 EDT

Arthur, a bunch of folks are moving to using foil due to the ease of use (no welding, no pealing off the tube). It also saves the forge. The trick is a roll of foil costs $70 for a 10 foot by 24" roll, $210 for a 50 foot roll.

A few years ago you could only find stainless foil in one material in 100 foot rolls. Today McMaster-Carr has 68 selections (three alloys, several thicknesses, different widths and lengths) and 13 different size heat treating bags.

The common material for this purpose is 309 SS, .002" (0.06mm) thick,
   - guru - Wednesday, 08/05/09 13:38:51 EDT

Alan, I think you have it. . either canister or container will work. I prefer container.
   - guru - Wednesday, 08/05/09 14:00:39 EDT


Here's a dumb (and off-topic) question, but if the survey was in 1785, shouldn't they have named it the Louis XVI Cadastre?
   Mike BR - Wednesday, 08/05/09 17:44:40 EDT

Canister is shot!

My personal feeling is that Vulcans are about the lowest of the "real" anvils and sure would not pay a top price for one! When I do get one I sell it on cheap.

OTOH I quite like my Fisher and wouldn't sell it for US$2000

   Thomas P - Wednesday, 08/05/09 18:08:18 EDT

I hate to cast doubt on what appears to be a good deal, but for those considering purchasing idler and drive wheels from SunRay, be advised they do not balance their wheels or idlers. The hubs are turned on CNC machines, but not balanced. Their low prices are for wheels they do not advise you to use above 800 RPM (look at their website). If you want balanced wheels, they will send them out for balancing, at more than double the cost (price varies by wheel size). The wheels you buy MAY work fine and perform like they have been balanced.... They claim many customers use them for high speed applications and have reported good results, but they do not guarantee them for those applications.
   - Dave Hammer - Wednesday, 08/05/09 19:37:54 EDT

Vibration: Last year at Quad State I got a 12" disc grinder that needed a motor. I put one on it, but it didn't run true & vibrated. After truing the mounting flange on the lathe it still vibrated. I did trial & error tests of a washer duct tapped to the back of the disc. Yes, the washer did fly off once, don't run more than enough to get it turning, then watch for vibration as it slows to a stop. I then tack welded the washer to the back of the disc. Vibration problem solved.
   - Dave Boyer - Wednesday, 08/05/09 20:21:56 EDT

I agree with ThomasP, Canister is shot!

ThomasP, ever see a 152MM canister round from a modern weapon? AWESOME is not descriptive enough:)
   ptree - Wednesday, 08/05/09 20:55:07 EDT

And BEEHIVE! is flacets:)
   ptree - Wednesday, 08/05/09 20:55:38 EDT

Dave's comment, This is related to the "Getting away with it" factor. Folks arc weld ball bearings together with no problem. Others do the same and under load the welds crack and their balls fall off. . . Some folks burn zinc off parts and get away with it, Paw-Paw dies doing the same. Lots of folks get away with things that don't work or are sometimes very dangerous. Some parts are in balance as made, but others are not. Depending on the speeds more may be sufficiently in balance than not, but at high speeds less. . .

So the trick is improving the odds OR balancing the parts yourself. ( I see Dave Boyer chimed in on this one)

Balancing is done a number of ways but determining the amount is often done by trial and error. Static balancing is done on knife edge balancing ways. The part is turned and should stay put in any position. If not then weight is added to the opposite (top) side. The amount is adjusted by trial and error. Temporary weights are used and then weight can either be permanently added OR removed from the opposite side.

Dynamic balancing can be done on a small lathe or drill press using a slightly whippy short shaft or one embedded in rubber and carefully reving to high speeds. Be sure the part and shaft are turning true first with dial indicators. Chalk is used to mark the high spot while reving (or you can guess by focusing on the high spot as the part slows down and stops. . ). Weights are then played with until the part stops vibrating at the working speed. NOTE however that most high speed parts vibrate at various critical speeds (that vibration as a grinder winds down). Criticals cannot be balanced out.

I used to balance auto wheels by trial and error using a spin balancer and no balancing head. I watched the heavy spot as the tire stopped then added weights to the opposite side. When it was right I divided the weights and put them on front and back, OR on alloy wheels where the weights were stuck on near the center line I just put the weight on permanently, it having been held on with duct tape while testing.

Test weights should be placed where they cannot fly off.

A small grinder motor armature that had drag wear was balanced by mounting on cushioned centers, run at high speed and then dressed (machined) while turning. As the high spot was reduced the armature balanced until no more needed to be taken off. The motor lasted many years after.

These are things you can sometimes get away with to reduce the "getting away with it" factor. . .

With high speed rubberized wheels you can often fix them by dressing the rubber while they run. Machining (point tool) works or grinding (tool post grinder with rotary file) works better.

But after all this you may decide that paying for the professionally balanced parts is cheaper, better, easier. . .
   - guru - Wednesday, 08/05/09 21:00:52 EDT

Mike, good point. Just dug around on the net - our local Marie appears to have the date wrong (or I misunderstood them - I wonder in they said 1795?). Decrees of 21 August and 23 September 1791 authorized the department directories to lay down the survey of the parcel (land)plan of the territories. However, a general parcel cadastre was not envisaged at this stage. A decree of the consuls of 12 brumaire year XI (3 November 1802) decided on a general cadastre in 1,915 communes. The law of 15 September 1807 was at the origin of the French parcel cadastre.
   John - Thursday, 08/06/09 01:49:05 EDT

I think flechette is the word.
   philip in china - Thursday, 08/06/09 09:22:59 EDT

Phillip in China
My bad. My spelling is often very bad:) I had the misfourtune to be born left handed, and go to school in a time when kids were forced to use their right hand to FIX them as far as using the wrong hand. Made my hate school, and since I did not apply myself, I did not learn to really read till I was in the third grade. I have always been a poor speller, and have had issues with school ever since.
Machine however are easy, as right brained dyslexics tend to think is pictures and think in systems rather than words and numbers.

If the right side of the brain controls the left side of the body, then only left handers are in their right mind :)

It is a poor unimagitive mind that can only spell a word one way :)
   ptree - Thursday, 08/06/09 10:00:48 EDT

I had a lot of issues with school as well. I didn't like change then any more than I do now so moving from school to school was always a disruption. From K to 7 I attended seven different schools and then three more to complete High School. We made two moves during that time. The first was the worst moving from an urban Northern area to a Rural Southern area where they spoke a foreign language that you were expected to understand . . I started out way ahead of the other students and then fell way behind due to boredom. I blame Dick Jane and Sally and their stilted speech talking down to children as if we were all retarded.

I've always been the one to ask "impertinent" questions and was not satisfied with answers that side stepped the question. Questions such as the one often asked in Sunday school about where did the wives of Kane and Able com from if Adam and Eve were the first and only people made by God? I expected teachers as adults in the education business to know a LOT. Sadly most knew just enough about their subjects to teach them. While the exceptions were probably 50% the ones that could not answer questions or did not think the questions of import were the ones that colored much of my world. Questions like why are there 24 hours in the day and 360 degrees in a circle (related questions).

When you read enough old literature and documents you find that modern "standard" English spelling was pretty much the decisions of one man, Noah Webster followed by G. & C. Merriam Co. with little regard to English spelling in England whence the language came. Today words are still added to the approved list by individual editors.

I suppose it is best that one man made most of the decisions. . . Imagine what a government committee would do? One hundred and fifty years later we would still be geting new "official" revisions to the dictionary and might be waiting for whole alphabetic sections to be agreed upon and completed.

There are many words that I learned the British spelling and still prefer. Words like "centre". But as time goes on there must be more standardization of languages so that translations can be accurately made. More change. . .
   - guru - Thursday, 08/06/09 11:34:05 EDT

No I have not seem much modern artillery in action; but I have had a lot more fun than I should have with my little 2" smooth bore falconette. Eats the single F though...

   Thomas P - Thursday, 08/06/09 11:37:56 EDT

ptree, I was told some years ago by a mechanicl engineer at Armstrong & Blum that, "A sure sign of a genius is someone who can spell the same word two or three different ways. "
I've been operating under that premise for years...
I'm also left handed and fought with my "teachers" over many things.
   - merl - Thursday, 08/06/09 11:40:26 EDT

I've just upgraded my system and the new version has an inherent spelling checker for most things. So now I have to put in the english spelling for many words I commonly use and it doesn't seem to do well with medieval or smithing jargon. Sigh.

My worst move was from right outside Washington DC to a suburb of Indianapolis IN in 1968---severe culture shock and with my father working for NASA I was more scientifically advanced than my 6th grade teacher was, I mean he told the class that "heavy water" was water charged with carbon particles and mainly used for traction in tractor tires! He did not appreciate me setting him straight...

   Thomas P - Thursday, 08/06/09 11:43:49 EDT

Guru, When I entered the ARMY, I learned the ARMY method of teaching, that is" see it once, do it once, teach it" In reality, an interested instructor will learn more from teaching than the students. Because every impertinant question is a learning oppurtunity. A GOOD instructor will always admit they don't know the answer, then find out the answer and communicate same to the entire class. In this manner, one learns a subject FAR beyond attending a class.

When I started giving technical tours to customers of the Henry Vogt Machine Co. I was handed a 20 page or so guide that had been made up for tour guides at the 100 anniversary. I was asked many questions by the thousands of folks I took thru that 40+ acre, several million square foot shops. Three distinct industries, and after21 years of doing tours I was still learning. When a teacher quits learning, they should either quit.

I instructed/jumpmastered skydiving for about 8 years every weekend. I quit when I found myself with less enthusim, and not searching for answers to questions that popped up that I did not have an answer for.

I still teach industrial safety as part of my job, and am still learning. Hopefully I will still have the enthusim for about another 10 years:)
   ptree - Thursday, 08/06/09 11:44:05 EDT

Thomas, you use single F in that thing?
I have a "device" that uses 4-5 cap fulls of 3F to great effect and employs a .22 blank for the ignition.
Great fun but, I have to turn my own wooden projies as, it is an odd size I.D.
   - merl - Thursday, 08/06/09 11:54:32 EDT

Interesting point about Sunray-ins.com wheels... I did not realize they were not balanced. I've either got really lucky ones, or I'm operating at a RPM where it doesn't matter yet.

In theory, I'm using a 1.5 HP motor at ~1725 RPM with both drive and idler wheel's being 4", so in theory EVERYTHING turns at ~1700 unloaded.

In reality, its a Harbor Frieght motor, so those numbers are, ahem, not precise.... I have no idea what the actual RPM is, but I could probably figure out a way to measure. Marking a spot on the belt and counting as it runs won't work, its moving too fast for that. If i had an old bicycle wheel and speedometer handy....

   Mike/Marco - Thursday, 08/06/09 12:07:32 EDT

Actual RPM: On induction motors the no-load speed at 60Hz is 1800, 1200, 900. . . Under load the motor slows down a bit or "slips" from synchronous. To go as slow as the rated RPM you must apply full load. So the RPM varies with load but will be no higher than synchronous. Note that motors run on 50Hz run proportionally slower.

You can tell a bit about the motor's durability by the difference between synchronous and rated RPM. The greater the difference the harder the motor is working and the hotter it gets doing the same job as one rated closer to synchronous. This is a generalization that is not always true but it seem to apply to the difference between new "high efficiency" motors and old inefficient motors. I think most of the efficiency is in the amount of materials used. . .
   - guru - Thursday, 08/06/09 12:50:46 EDT

Education and Reading Materials. . .

When I was in elementary school my Dad had a subscription to Science Newsletter. It was a small thing with articles on scientific breakthroughs, new patents in the sciences and such. So much was happening then (the 1960's) that it was really exciting reading. It was completely different vocabulary than ever taught at school and WAY beyond the Dick, Jane and Sally crap that I was still having foisted off on me at school. . .

Being a little geeky I had all the How-and-Why science booklets, a chemistry set, microscope and so on. We spent most of our time studying how to make things that blow up but THAT IS largely the history of chemistry. . . Nobel's dynamite is still the money awarding the big prizes in science.

Then there were the old science series and Dad's Machinery's Handbook. At home I was reading about the advances in LASER's, the tectonic shift theory (it was still a theory then). I would look things up in the encyclopedia when curious but also read the Sunday and daily newspaper comics and somewhere in there read all of the James Bond 007 books, some Playboy and National Geographic.

No wonder I was bored with school and use creative spelling.
   - guru - Thursday, 08/06/09 13:21:33 EDT

I read wher Dr. Seuss (Theodor Seuss Geisel) wrote his first books, in part, as an antidote to the blandness of the Dick and Jane readers.

I, too, was known for "daydreaming, doping-off and not applying himself." The school psychologist's conclusion is that I was bored out of mny skull. Never really hit my stride until I reached college.

Years later, while sitting on the church vestry, we were invited to a talk form the former head of Montgomery County, Maryland schools; then one of the leading school systems in the U.S. When he used the phrase "...but you always have some kids daydreaming, doping off and not applying themselves." I had to bite my tonguue very hard, both from astonishment (Is it a stock phrase? Did he talk to my parents?) and to keep from confronting him.

On the other claw, given the wide variety of people and needs, and the limited resources for educating them (just ask my friends who are teachers, they know the score) it's amazing we get as good a result as we do, most of the time, in most places.

Creative spelling is fun with friends and family; but in the "gummint" I have to get everything right; y'all don't want to be represented by somee yahoo, right? ;-)

Back to the work of the republic.

Visit your National Parks: www.nps.gov

Go viking: www.longshipco.org
   Bruce Blackistone (Atli) - Thursday, 08/06/09 14:41:45 EDT


It doesn't suprise me that you have no issues running Sunray 4 inch wheels at around 1725 RPM. Especially if you have them solidly mounted. If you can get your grinding done at that speed (around 1800 Feet Per Minute), that's great. Many folks want to go to as fast as 6000 FPM though, sometimes with larger drive and/or idler wheels. Most accomplish the speed using a pulley on the motor to a smaller pulley on a mandrell (which has the driving wheel on the other side). Speed and mass are serious enemies of unbalanced wheels.
   - Dave Hammer - Thursday, 08/06/09 15:51:05 EDT

I may need to clarify that Feet Per Minute is the surface speed of the sanding belt.

Also, it's likely that Sunray is being extremely conservative on it's speed recommendation. I doubt it would be unusual for a safety spec to reflect half the capability of the product.
   - Dave Hammer - Thursday, 08/06/09 15:57:54 EDT

One way to drive my wife nuts is to read French but pronounce it like Spanish. I did this the other night when we unboxed a new toaster. 15 (!) pages of instructions and warnings for the toaster. Then repeated in French and Spanish. Didn't know I had such a deadly tool in my hands. She didn't think it was so funny after the third page
   - David Hughes - Thursday, 08/06/09 16:03:15 EDT

My woodworking band saw runs almost 6,000 FPM and when a blade breaks it is a huge crash. About 1/3 of the blade ends up accordioned on the wood or table and several more feet in a knot above the guides. When I hear the first ticking of a cracked blade I hit the off switch but it is usually not fast enough. There is no rewelding a blade after all that. High speeds are scary.

I've had belt sander belts flip off an hit me. Its a good reason for guards. If you do not build full enclosing guards then at least bars that prevent the wheels from flipping a long piece of belt.

Running machines slower has advantages.
   - guru - Thursday, 08/06/09 16:06:50 EDT

Do yoou know if anyone distributes Kuhn air hammers in the US? Thanks
   mike - Thursday, 08/06/09 16:52:36 EDT


You sure convinced me not to try welding ball bearings (grin).
   Mike BR - Thursday, 08/06/09 18:38:35 EDT

A quick note about the New England Blacksmiths Fall Hamer-In-

Due to overwhelming requests, we have ramped up the Green Coal portion of this event. We will have 6 fully equipped forging stations open for all attendees to learn on, as well as a professional, experienced smith on duty at all times to teach, explain, or help out as needed.

Steve Parker will still be the featured demonstrator, and Nathan Robertson will demo making one of his excellent hammers.

There is also now a printable PDF version of the registration form on the New England Blacksmiths website, as well as a schedule of events. http://www.newenglandblacksmiths.org/spr..._meets.htm
   Judson Yaggy - Thursday, 08/06/09 19:01:16 EDT

When making home made tools, why can't seasoned oak be used ? It is hard enough, you can't drive a nail in it or put a screw in it unless pilot holes are drilled first. It can be worked to the desired shape, and planed for a smooth surface...just wondering.
   Mike T. - Thursday, 08/06/09 19:14:28 EDT

Mike, in my opinion, oak is a brittle wood that tends to split rather easily compared to ash, hickory, etc.
   quenchcrack - Thursday, 08/06/09 19:17:03 EDT

Atli, whatch y'll got 'gainst Yahoos? I think Jethro Bodine was a well eddicated man!
   quenchcrack - Thursday, 08/06/09 19:19:52 EDT

While on the subject of home built grinders, don't overlook old jet type or shallow well water pumps as a motor source. Most are 1/2 HP or larger 3450 RPM. I have a 3/4 HP on My 6x48 belt sander. They are face mounted, and not intended for easy reversal, but in a scratch built machine You can work around that. I had to find the junction of the start & run windings inside to reverse it, and weld the proper mounting hardware to the case for My aplication, but it has ben working that way over 25 years. There is a 3 HP in the future project pile...
   - Dave Boyer - Thursday, 08/06/09 20:07:22 EDT

Centaur Forge sells Kuhn and are the exclusive US distributor.

They have not pushed the hammers or advertised them separately since Bill Pieh died. I thick they are doing the line a disservice and are missing a lot of sales.
   - guru - Thursday, 08/06/09 20:19:41 EDT

Dave Hammer:

At that belt speed, with a water drip, heat treated 5160 steel disappears without over heating, so it seems to work just fine for us. With Norton Blasze belts in 60 grit, I make a LOT of steel wool looking waste while carving a blade into shape.

The grinder as shown/described above weighs in at about 60lb without the motor. HF says the motor I'm using weighs 40lb. Since I need a set of pulley's on the sho rafters to move this thing safely, I think they're right. In addition to being ~100lbs, the wheels are running on 1/2 grade 8 bolts into 1/2 plate. All in all, its pretty solid.

I'd thought about running one faster for materials that aren't heat treated, but not with these wheels, I guess.

   Mike/Marco - Thursday, 08/06/09 22:22:10 EDT

can you use stoker coal in a forge?
if you can do you have to keep it wet or anything?
is it ok when your in a pinch?
all i have used is coal that is used by the blacksmith instructor at southern illinois university of carbondale and it is very good but it is 500 miles away and i can get stoker coal 100 miles away would it be ok?
sorry about all the questions and thank you guru...jim
   Jim Midgley - Thursday, 08/06/09 22:37:19 EDT

Marco and all,

If the Sunray wheels are not balanced, here is a web-site
you can look at for a grind wheel balancer...about $64 bucks. Guru see if this would work.
   Mike T. - Thursday, 08/06/09 23:22:55 EDT

JIm Midgley,

I think that stoker coal is simply coal that has been screened to a certain size. You won't know how well it behaves for smithing coal without trying it. Coal from different mines is almost infinitely varied. Some is shiny; some dull in appearance; some coal is slatey; some has many fines; some has sulphur streaks, rocks, etc. What you want is a coking grade that has a good BTU rating for our kind of work. In the current coal industry, it is called "metallurgical coal." In the old days, the smiths called it "blacksmithing coal" or "smithing coal."

Whether to wet the coal depends on its size. If pea size mixed with a little bit of fines, it can be wet down to pack it around the sweet spot of the fire. It is packed so that it is steeper than the dry coal angle of repose. Good coal in use, will make a "coke ring" around the sweet spot. Feed the fire by chipping coke from the ring. More green coal is added, wetted, and packed as needed.

The fire is a high or deep fire, so that when possible, the workpiece is put in horizontally, not angled like a dipstick.

If the coal is in large chunks, wetting it does nothing, unless the fire is spreading sideways rapidly.
   Frank Turley - Thursday, 08/06/09 23:27:59 EDT

Mike T,

That One-Way balancing system is a great thing for balancing grinding wheels, but it will not work on contact wheels for belt grinders. It relies on special flange washers for truing the axis and concentricity of grinding wheels and is designed to work most conveniently on wheels with a 1" arbor hole. It won't work on wheels with bearings in them, though.

As the Guru has noted, you can true a wheel on a lathe using a shark cutting tool or tool post grinder. That will get the wheel concentric. Often that is enough to take care of most balance issues, since they arise from irregularities in the urethane/rubber/plastic surface bonded to the wheel.

If the wheel itself is machined, as the SunRay wheels are, it is likely to be pretty darn accurate and therefore close to balanced. The real issue comes when you ramp one up to 5000-6000 sfpm and centripetal force exacerbates any tiny irregularities in the machining, material density or bonded surface. The only way to really correct that is with dynamic balancing the way it was described. There are fancy, expensive proprietary machines to do dynamic balancing and companies that will do it fairly reasonably, considering what the equipment costs.

If you plan to run an 8" or 10" contact wheel at speeds upward of 5000sfpm yo would be well advised to bring it up to speed progressively while checking for dynamic balance problems. If you have none you're in good shape, but if you do you might want to consider sending the wheel out for balancing and truing. A properly balanced, true wheel makes a large difference in the quality of the finish it produces.

One thing that should be mentioned here is that out-of-balance vitrified grinding wheels should NOT be run at all. Not only will they do a poor job of grinding, but there is a very real danger that they will suddenly come apart, flinging shrapnel all over the shop at frightening speeds. People have been killed this way.
   vicopper - Friday, 08/07/09 00:19:42 EDT

Stoker Coal: Everything Frank said above is correct. However, I think due the automatic nature of a stoker the coal must be a little better than average. All I have used was very good but it was from a supplier that kept nothing other than top grade coal.
   - guru - Friday, 08/07/09 02:37:34 EDT


What is a shark cutting tool? I tried looking it up, but no results.
   Mike T. - Friday, 08/07/09 08:58:49 EDT

Mike T, I suspect Shark=SHARP
   Ptree - Friday, 08/07/09 09:52:25 EDT

Grinder drawing:

I added "measurements" and a larger view of the head plate.

I cannot stress enough that YOUR measurements and actual machine may vary. This is designed/built on the "junkyard" concept and depends on structural materials you have at hand, size of the wheels/motor you use, etc.

With 4" wheels, the TARGET measurements between wheel centers are 9", 25", and 25". Smaller and you'll need to indcrease the tension arm size. Larger and a 72" belt won't fit.
   Mike/Marco - Friday, 08/07/09 10:40:12 EDT


Ha ha, Actually I did find a shark cutting tool, but it looked like a carpet knife.
   Mike T. - Friday, 08/07/09 11:55:14 EDT


I really like your diagram, everything is clear. You should have been a draftsman. I have printed it out.

Thank you very much
   Mike T. - Friday, 08/07/09 12:02:34 EDT

Sunray Wheels:

I have heard on another forum of one knifemaker who had an out-of-balance contact wheel from them. The remedy as mentioned and proven by several other knifemakers on that forum was to tell sunray up front what you're going to do with the wheel and ask them to balance it for you. They will. Problem solved. You do have to ask when you order, though.

Also, the only wheel you need rubber on is the contact wheel, if you're using one. The drive wheel and all idlers should be bare metal. A little crown on the drive and tracking wheel is handy, no crown on platen idlers or contact wheels.
   Alan-L - Friday, 08/07/09 12:22:15 EDT

Mike T,

Here in the islands, everyone has a shark cutting tool under the seat of the truck. Just in case, y'know? :-)

As Jeff said, I meant sharp. For cutting rubber or plastic on a lathe that generally means a special grind on the cutter bit. I've messed around and gotten lucky a couple of times, but someone here probably knows the proper angles to grind the cutter at and will post them.
   vicopper - Friday, 08/07/09 13:14:42 EDT

Turning urethane rubber in a lathe: I had the best results with a really pointy narrow tool and a heavy cut. Rather than making chips, the material removed came off like a rubber band peeled from the diameter. The narrow tool is nearly parallel to the diameter. I never needed to make a long cut, but I guess the removed material would eventualy tear. The parts I made were made from 1/2" thick sheet goods, If I remember right, We glued it to a chunk of wood held in the lathe chuck.
   - Dave Boyer - Friday, 08/07/09 19:51:30 EDT

To machine rubber easily you freeze it. Dry ice will work. Just gotta get it in the lathe and work fast, have all your setup done ahead. . .
   - guru - Friday, 08/07/09 20:56:18 EDT

MikeT, thanks for the compliment, although I have to say its not really earned. My father is an engineer, and tried to teach me thsi stuff when I was a kid, but I knew better. :) Now that I know less, I wish I'd paid attention. What I've done is easily accomplished in Microsoft Visio, which lets you make anyhtign from flow charts to intricate mech/elec engineer diagrams with little chance of error. All thos emasurements are built in, as are the bolts, geometric shapes, and a background "snap" grid. That drawing took no great skill, only the imagination necessary to drag boxes into place and shape. :)

As for the design, I try to think about machines sort of the way Guru once described [pardon the inaccurate paraphrase]: Picture the working part you need [where the hammer hits, where the grinder belt need to move], and what kind of power source you have [motor, air cylinder, etc.]. Everything else in-between has been done a thousand different ways, pick one.

Metal vs. rubber wheels
your mileage may vary, but I use the rubber wheels for idlers and tracking because the original aluminum one's I had all wore away within a few hundred hours of grinding time. Separated abrasive and metal bits were getting behind the belt and eating away the wheels as if the belt were on inside out. Also, in the current configuration depicted, I sometimes use the upper platen wheel as a contact wheel. Today I noticed that my drive wheel isn't crowned anymore, its slightly conical. The rubber wheels get some grit embeddes, but haven't worn measurably in more than twice the grinding hours of the aluminum ones.

   Mike/Marco - Friday, 08/07/09 22:03:45 EDT

Cast iron question:

I should know this, but don't. Can cast iron be magnetic?

I have an old outdoor table, a family heirloom of unknown real value, which broke in a storm. The preaks are all in places which ought to be easy to weld, but I'm not sure what material it is. The pieces are clearly cast, assembled with bolts through holes and overlapping tabs, and was purchased in the 50's or 60's for a high price at the time.

It is magnetic, grinds like steel to a bright finish, but down't have any particular ring when thick parts are struck with a hammer. On the inside of a leg, in a thick place, I laid a small weld puddle with mild mig wire and CO/Ar... it welds like steel.

Aside from a spark test [will try tomorrow if I can find a cast iron sample], any thoughts on how to tell if this is steel or cast iron?
   Mike/Marco - Friday, 08/07/09 22:54:28 EDT

Mike, It really doesn't matter if it's steel or cast iron. You can weld some cast iron items with a mig welder using mild steel wire. Years ago while I was still working in the theatrical scenery business we used the mig to weld parts to old cast iron lamp posts with good effect. It's not an unusual application. If it works it's good! If it doesn't you can always revert to the old standy of braze welding the parts that didn't take. Steve G
   - SGensh - Friday, 08/07/09 23:12:06 EDT

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