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Old 08-10-2008, 03:43 PM   #1
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Default Buying valve shims? What a joke!

For all those who thought you should buy your shims when you need a thinner one, you've been wasting your time!

While sanding takes about an hour per 0.001", and putting them on the lathe at best makes grooves while your bits smoke and break, and this last one... It does remove material, but not much before the stone loads:


Anyway, no time for preamble today. Here's what I did, an it worked. It's what I'd call "emergancy repairs only", but it does work for grinding hardened stuff materials in circularly symetric ways.



This lets you get a feel for how much you took off, since the the stone goes away pretty quick



The problem is the stone seemed to wear as I went from center to edge (doing it again I might run the lathe slower). This gives a few mills of "cupping" which is actually nice, since you can set the final dimension by sanding. I used a vavle lapping suction cup stick thingie for the sanding, and you have to wet sand (squirt bottle of water or alcohol) to keep the paper working. I used 80 grit, then 200-400-600 to polish it up, and face that side down.

Post grinding:


Final product.


Other notes: One shim makes a good backing plate for another, but you have to tighten it a lot. You can crack the shims if you bite on their edge. Something I did, I forget what, made it bite much better than in this video, but this at least gives you an idea for what it's like:

http://video.google.com/videoplay?do...82554346&hl=en
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Old 08-10-2008, 08:03 PM   #2
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Hmmm. That lathe looks VERY familiar.

Glad you're getting some good use out of it. It's such a nice tool to have for this sort of quick oddball stuff.
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Old 08-10-2008, 08:34 PM   #3
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cool
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Old 08-10-2008, 10:31 PM   #4
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Hmmm. That lathe looks VERY familiar.

Glad you're getting some good use out of it. It's such a nice tool to have for this sort of quick oddball stuff.

I have one, too. Not the Harbor Freight, but similar enough not to matter (longer bed, for one thing). Got mine for less than 300 bucks through Homier. They were over 400 last I looked.

The ways and gibbs are crap, I spent almost a year tuning it enough so it would't chatter. Stll can't cut copper, but it does a nice job on brass, and aluminum comes out really nice. I mostly use it for small hobby type stuff.

I used it to cut down the bushings that came with the ISC tophats, as they were too long. Did a really nice job of that.
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Old 08-11-2008, 03:02 AM   #5
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uh huh, this one needs some work to make everything run right - just some re-greasing, tightening, etc. It definately misbehaves if you abuse it, but it overall decent. I've already made some banjo bolts and other oddball things on it.

too bad a certain someone skipped town without leaving behind all his metal stock. :-)

But the whole dremel-in-the-holder thing seemed wild to me. Sure was noisey.
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Old 08-11-2008, 09:55 AM   #6
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makes me laugh when Neo used glass and sandpaper for his.
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Old 08-11-2008, 10:11 AM   #7
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does the shim surface just look rough in the photo? I hope so.
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Old 08-11-2008, 10:26 AM   #8
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Take out the gibbs on both the feed and cross slides. They're brass, and the finish on them is crap. Mine were just rough milled, and not parallel at all. I lapped them using sandpaper laid on glass, and smoothed them out (what a pain-in-the-*** job!). It made the feed much more stable. It also allows you to tighten down the screws to remove more play without binding.

Also, if you're having a tough time getting the finish you want on harder materials, invest in some carbide bits. They are tougher to sharpen, but the will give you a much better surface finish, and a lot less chatter. I brought mine into work (we do precision diamond maching here) and had one of the techs put a perfectly lapped edge on mine. The difference in cuttting was amazing.
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Old 08-11-2008, 01:01 PM   #9
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makes me laugh when Neo used glass and sandpaper for his.
I tried that and it didnt work. So the correction is:

Neo used a diamond coated knife sharpener.


I could remove 0.001" every few minutes with it. By far the best thing to use. The fixture and lathe thing is cool and all but highly unrealistic for most. Diamond plated knife shapeners eat through hardened metal and are available in every local Lowes, etc... for about $10.

It just took me like 10+ hrs because I had to do 16 of them and I have to remove multiple hundredths on each.
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Old 08-11-2008, 02:21 PM   #10
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Take out the gibbs on both the feed and cross slides. ... It made the feed much more stable. It also allows you to tighten down the screws to remove more play without binding.
Hey - thanks! I was looking at where to start. And with a few weeks of not driving ahead of me, I should have time on my hands!

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I could remove 0.001" every few minutes with it. By far the best thing to use. The fixture and lathe thing is cool and all but highly unrealistic for most. Diamond plated knife shapeners eat through hardened metal and are available in every local Lowes, etc... for about $10.

It just took me like 10+ hrs because I had to do 16 of them and I have to remove multiple hundredths on each.
Interesting. Sandpaper worked for me, but yeah, it was very slow.

You know you can buy shims, right? :-) Through mazdacomp they are almost not too expensive. And after the third time, you have such a stock of them, you mainly just swap them around.

You did give me one good idea, though - I have diamond bits, I didn't even think of putting them in the dremel - the roughness you see (I PUT THAT SIDE DOWN!, and sanded the bottom for finish) is the stone breaking away, hence it's thicker at the edges than the middle.
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Old 08-11-2008, 02:46 PM   #11
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The mazdacomp ones are *** rape compared to the bag of 16 caps I got for like $15. I was doing shim under bucket mind you.
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Old 08-11-2008, 04:08 PM   #12
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Hey - thanks! I was looking at where to start. And with a few weeks of not driving ahead of me, I should have time on my hands!
Check out http://www.mini-lathe.com/ Everything you need to know, plus all sorts of fixes, improvements and adjustments. Some of the links take you to pages of guys doing incredible work with these machines. Some are as obsessed as we are with cars.

I started making miniature steam engines with mine. Pretty sloppy amateur work compared to a lot of the stuff out there, but it keeps me busy when the weather is crappy.
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