How to make thin shim washers

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Well-Known Member
Sep 27, 2007
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I was working with a small (.020 cu. in.) Russian glow model airplane engine a few years ago and needed to decrease the compression via adding a shim/gasket under the glow head. The ones I had on hand fit a Cox .020 and were too small. After much head scratching I came up with this method which worked well.

I cut out a bunch of small squares of aluminum & brass shim stock in various thicknesses, (.003" to .008") and stacked & clamped them tightly between 2 bits of flat steel.


I then drilled/reamed the stack to the desired i.d., took the stack of shims out and clamped them on a bolt & nut between washers. I chucked that lump into the lathe between centers and turned it down to the correct o.d.


When the shims were removed from the bolt, they were perfect! That crappy engine still didn't run right though.

Very good tip there Milton.
I love these little quickies that use basic materials and take little time to do. No excuses now for having sloppy fits, just shim it up.

I'm new to the forum and thought i could contribute to this. For making reed valves for a pulsejet I was working on I used .006" shim matl. painted both sides well, scribed the shape of the valve, scraped paint of the corner of my shim stock, hooked one end of a battery charger to the corner of the shim, the other end from the battery charger to some scrap metal, then dropped the shim and the scap in a plastic bucket of salt water and turned it on. the higher the amperage the quicker it finished , the lower the amperage the cleaner the cut. This would work great for someone with out tooling.
zeusrekning, welcome aboard!

I am interested in you method of cutting thin stock with this method. Would you mind starting a thread outlining this technique? I can see where any shape could be made using this method for things such as gaskets or shims needing some odd shim. This may benefit many of us.