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
- 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
- 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