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All Springer/NP/PCP Air Gun Discussion General > Machine Shop Talk & AG Parts Machining

Precise washers, any tips or techniques to get the thickness just right?

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WobblyHand:
This is a technique question.  I'm trying to make a washer shim to clock a non-circular moderator correctly.  I machined my moderator adapter to have a wide flat surface as a reference.  I'm off by exactly 180 degrees, or 1/2T at 20 TPI.  So I tried making a 0.025" thick washer.  I got close at 0.0275", but that is still about 18 degrees off.  I indicated the parting blade, so at least the washer is flat, not domed!

Where I'm actually struggling is setting the zero for the parting blade.  I was trying to use a straight edge on the part and seeing if the parting blade just catches the straight edge.  It seems that I'm not so good at detecting the parting blade interference or maybe there's a bur on the edge of the blade.  Can anyone offer a suggestion that might be easier or work better?

I can fix what I have, but I'm really searching for a better solution for getting zero for the parting tool from a faced surface.  Any suggestions?

Psipumper:
Usually for things that thin , I use shim stock and a shim cutter.
On the lathe if your parting tool is wide enough the washer can be measured with calipers before completely cutting through and be adjusted to measure.

WobblyHand:

--- Quote from: Psipumper on August 04, 2024, 06:08:03 PM ---Usually for things that thin , I use shim stock and a shim cutter.
On the lathe if your parting tool is wide enough the washer can be measured with calipers before completely cutting through and be adjusted to measure.

--- End quote ---
Interesting idea on measuring before cut off, hadn't thought of that.

Watched a Joe Pie video on cutting a bunch of thin washers out of shim stock.  I don't have piles of shim stock, I do have some, but actually not in the right thickness.  But, I did save a bunch of aluminum cans and cut them up.  I could stack them together and try to get to 0.025".  The hard way, I know, but it's another possibility.

For now, I might superglue the slightly thick washer onto a rod and face off a few more thousandths.  I have two washers that I made, maybe one of them will end up little closer to being right.

JuryRigger:
I'd personally be tempted to 'lap' the washer down that last 2.5 thou on a decent bench stone-do a figure-8 pattern and keep checking for parallelism every now and again...
Starts going off, then stroke it with the high side facing the direction of travel, doing a straight line-the leading edge will cut deeper than the trailing...
Jesse

WobblyHand:
Apparently my superglue is well past expired.  Darned stuff wouldn't cure.  Washer kept on falling off!  So I'm at the oh so slow method of sanding/polishing this stupid washer.  I have it down to 0.025" thick and a have a few more degrees of rotation to go.  That's under a half thousandth to go.  At 0.025" thick there's not much to hold on to.  I need to make a little holder as it's hard to apply any pressure.

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