There are two Joe Pie videos on YouTube called:

Machining ultra thin shaft spacers and precision washers

How to Hold and Bore Out Thin Shims

These may give you useable ideas.

Martin C

Similar to the above post by Neil and the reference to Joe Pyzynski is how I make washers. The machining jig below on the left was used for making copper washers 42mm ID x 58mm OD x 1mm thick. (similar jigs used for smaller dia. washers 0.25mm thick).

The shim material was roughly cut, slightly bigger than required and sandwiched between 2 square plates. The plates clamped together with bolts at each corner and mounted in a 4 jaw chuck on the lathe. Then drill/bore a hole thru the complete assembly to the the required ID.

Remove from the end plates and mount in a jig as shown for turning the OD. (cardboard shown as example only)

Clamping the washers together with a solid plate on either end eliminates any roll-over and produces a sharp machined corner. (On very thin material it is best to make a number of them at the same time)

Edited By Paul Lousick on 10/01/2023 06:07:36

I’ve made big end shims for connecting rods by clamping multiple layers of shim material between jigs and hand-working/machining to size. OK, like Paul above, if circular and of sufficient thickness. However, for thinner shims I have found it better to grind to shape, rather than cutting by other means because I got better edge thickness that way. There is not just one way ‘to skin this cat’, depedent on the required finished product.

There is a way I have used which does not require a lathe or column drill – an ordinary electric hand-drill, and an ordinary bench vice was all I had access to. But I did have a selection of hole 'drills' – the sort which has a central boss carrying a twist drill of 6mm (or 1/4 inch). Around the boss is a thread onto which can be screwed steel tubes in various sizes, with the end of the tube formed into saw teeth. One name for such things is 'Hole Saws' – and plumbers use them to bore the holes in the sides of your kitchen fittings.

You will need two of the saws themselves, one to fit inside the required shim, and one to go outside it. Now you need two oddments of plywood, one fairly thin (8mm +/-) and the other rather thicker, both a bit larger than the finished shim should be. Use the twist drill to bore a hole in the middle of the thin plywood, and clear off the splintery edges to leave smooth surfaces. Clamp a piece of shim material between the two plywood offcuts, and clamp one edge of this bundle in the vice, leaviung the whole surface area of the desired shim visible. If you have a small G-clamp or a similar tool, add it to the free edge to hold the two sheets of ply tight against the shimstock. Set the hand drill to a slow speed, and fit to it the smaller of the two hole saws. Guide the twist drill into the prepared hole, and drill slowly through the thin ply and the shim behind it. A squirt of oil will help. Lift out the disc of ply, and the inner off-cut of shim – carefully as the edges will not be nice and smooth. Now fit the larger hole saw, and repeat the operation, relying on the hole in the thick plywood to maintain concentricity.

This should produce a reasonable shim, which is likely to need trimming to neaten the edges, and it can be held in vice between the remains of the plywood to do this. If the shim material is thin (as they often need to be to take up clearance) you could trim the outer edge using tin-snips or a reject pair of scissors (when no-one is looking).

Don't be tempted to hold the assembly in your 'spare' hand as you do the drilling. If things start to go wrong you need to keep all your organs well away from spinning sharp edges … And if you are not sure, don't try and hope for the best. Gambling is never worthwhile.

Regards, Tim

Electrochemical etching? Can make odd shapes that way.

I used to rebuild lots of car differential units. This work calls for a fair bit of shimming to achieve the correct bearing preloads, gear mesh & engagement depth. Unfortunately the shims only seem to come in bulk packs of the same size from the differential manufacturers. I'd have been quite some way into 3 figures of £££s by the time I had bought a full set of each size (and would have ended up with several lifetime's supply of shims). My solution was (and is) to use a pair of chassis punches to punch the inside and outside in steel shimstock.

These and other punches were bought off ebay for not much money; but I have made smaller size punch & die sets at home from silver steel, turned all the parts and used a flycutter to put the cutting radius on the punch before hardening and tempering.

Hi, I have made shims in the past using Paul Lousick's method, but for many years I've made shims from shim stock by clamping pieces of the stock, cut into a rectangle using shears, to a flat disc that has a shaft on it, so it can be mounted in the lathe and then cutting the shim out from the stock.

Cutting shims from this is not trivial, but it can be done, and with practice it can be done very quickly. I've used a watchmaker’s graver (difficult to keep it steady), a sharpened up piece of hacksaw blade held in the tool-post (tricky, needs to be very sharp and not to have any top rake or it digs in badly especially when breaking through), and, best of all, a small air die grinder held in the tool-post (using a small cylindrical wheel held at 45 degrees).

I scribe the ID and OD on the piece of shim and then in the lathe I centre it and tighten the clamp screws, which have washers under them, and then start the cutting. You cut out the inside first and then the outside. The cut edges are sharp and I often tidy them up using a small abrasive mounted stone.

I use this device mainly to make shims needed on classic motorcycles, typical shim thicknesses are in the range 3 to 12 thou. The pictures below show the tool used to hold the shim. I tend to drill and thread holes as demanded by the size of shim to be cut. It takes me about a quarter of an hour to make a shim provided that the shum doesn't snag when breaking through (the die grinder method more or less obviates that). I hope that helps.

To make accurate thin spacers I use a bar turned to the correct OD and bored to the correct ID. I face off the front face and then part off a spacer thick enough so that the front face remains reasonably flat.

I then use superglue to stick the front face of the spacer to the lathe's face plate and then slowly face off the spacer to the thickness needed. I have a DRO so can zero the DRO with the cutting tool against the face plate surface so it effectively reads the spacer thickness. Thinning down does have to be done slowly so the spacer doesn't detach from the face plate.

A rather tedious process but if you only need to make a couple of spacers it works well enough. I release the spacer with acetone.

CS