Making shims to adjust semitone forks

I use brass shim in four thicknesses:

• 1 thou (inch)
• 2 thou
• 3 thou
• 5 thou

The shim can easily be cut with sharp scissors (no not your wife's embroidery scissors!). The difficult part is getting a nice clean hole in the centre of the shim - here's the trick.

You need to make little punches to cut the shim. The way I did it is very cheap and works a treat:

• Get some scrap steel pieces about 10mm thick.
• Buy a selection of drills - 2mm, 3mm, 1/8 inch and 5/32 inch
• Drill a piece of steel right through with one of the drills - fairly close to an edge (you will need a drill stand to get a clean hole)
• Saw the fluted bit off the drill with a hacksaw - HSS drills are very hard at the tip and on the flutes, but more soft on the shank.
• Throw away the fluted bit and use a round needle file to file a concave curve at one end of the shank - this makes the cutting end.
• Use a fine blade (junior) hacksaw to cut a slot in the steel block - this is where the brass shim slides in.
• Slide in some shim, put the shank in cutting end first and tap the other end with a small hammer
• Remove the shank and you should now have a clean hole in the shim
• To complete - just cut round the hole with scissors - don't try to make it round on the outside, just cut a square and then cut off the corners to make an octagon.
• Make other punches using the other drills

Note: - if you are making new semitone forks, file them down to get the correct orientation rather than using lots of shims.

Various sizes of shim punch

Home