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Slitting Holes

Demonstration by Jock Dempsey
guru at!
August 9, 2000
Tonights demo will be a continuation of last week's.

Last week we discussed punching holes and slitting. Tonight we are going to look at how far to slit and what we can do with it.

Figure 15

Figure 13

Figure 14
A little logic will tell you how long to slit for a punched hole. For a square it is the length of two sides minus about 5% to allow for drifting a snug fit.

Figure 16
For round holes it is a little tricker.

Figure 17

Figure 18
The minus 5% lets you round PI to an even 3 (whoops) and the adjusted length of the slit is 3 time the radius.

Figure 19
For punching square bar on edge you need to start by forging a narrow flat to set the chisel on. After making the flats mark the length of the slit on the flat.

Figure 20

Figure 21
There are several ways to support the work to split it on edge. Supported on the anvil shelf, in a set tool (shown) or on a swage block.

Figure 22

Figure 23
Split the work about to center and then turn it over and finish from the other side. When done close up the split and square the stock back up.

Figure 24
Now to make something. Above we have split the bar several inches (about 5-6 in 5/8 bar).

We can open this up to make this pleasing shape made of triangular bar. . .

Figure 25
The open oval shape can be used on its own or we can continue to mash it down like this.

Figure 26
Then it can be flatten and the ends pointed as shown. For the mass of these corners to work out you need to bring the side points up to a welding heat and reweld just a little back into a square when you point it.

Figure 27
This one has had the bar cut off and pointed on the end too. This gives us two different shapes. A four pointed star and a mid bar element.

Figure 28
Using these two elements and more square bar split on the corner you can produce this VERY distinctive piece. All using the same techniques.
Very stout. Makes an ugly looking weapon too. . .
Jock, didn't some of Francis' work on display at Flag have that detail?
It may have. The first time I saw this was at the Ripley, WV conference in 1984. Josh Greenwood made one at an open forge just showing off!
PUNCHING PART I Punching Holes

Making Matrix and specialty Punches Touchmark, character and eye punches.

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