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Thread: Homemade lapping compound
02-13-2012, 05:49 PM #1
Homemade lapping compound
I have a major shutdown coming up and am looking at having to do a ton of lapping and polishing when we do tear down and rebuilds. ??Would graded silicon carbide powder($4 to $12/lb) mixed with 50/50 mineral oil and light grease work as well as "Clover Compound"? Making our own would save a bunch. Any feedback appreciated.
the old sailor
02-13-2012, 06:20 PM #2
You would need 2240lb less the weight of the oil to make a ton of lapping compound. Or 2000lb if you are in the USA.
02-13-2012, 06:21 PM #3
Personally, I wouldn't mess with it. You are already saving x$ by reconditioning a sealing or bearing surface. But if its comming out of your pocket, you'd be surprised what you can do with toothpaste.
02-13-2012, 06:28 PM #4
I lap on a daily basis with Clover. I used to by dry but would never do it again. I like the consistency of premix and really don't like the hassle of mixing. Dave
02-13-2012, 06:28 PM #5
I lap on a daily basis with Clover. I used to buy dry but would never do it again. I like the consistency of premix and really don't like the hassle of mixing. Dave
02-13-2012, 10:50 PM #6
What are you trying to lap. If you are trying to lap some half inch valves, use the Clover. If you have an 8 foot runner to repair, forget buying that stuff.
Buy the Silicon Carbide in big carboys, lard oil in barrels,and kerosene. Mix, drip, and lap.
02-13-2012, 11:15 PM #7
I use the garnet grit used for sandblasting for very coarse lapping... Makes stones flat in no time when rubbed against glass..
02-14-2012, 06:22 AM #8
YEARS ago my dad used to buy military surplus plug in radio crystals 10 for a dollar. He would remove the silicone crystal (4 screws) and grind it using Comet Cleanser on a piece of glass to change the frequency to use in C B radio base stations. At the time (1950's) IIRC C B crystals were $5. each!
Don't know if the Comet would work for you but he sure did some fine grinding with it.
02-14-2012, 07:22 AM #9
I recently lapped a 1 5/8" brass tube to reduce the out-of-round error it came with. Used as a cylinder in a replica of James Watts original experiment
Since the only lapping compound we have sittin around is really coarse, i used Ajax, a brand of household cleaner. Seems to be a mixture of something like diatomaceous earth, soap and sand. I mixed it with some kerosene, let the sand settle, poured it off, let the fines settle, poured it off, mix the fines with oil and go !
Worked fine. Obviously way too much trouble for anything bigger or any serious number of workpieces.
You gotta be careful, sand with grains as big as 10-20 thou is not exactly what you want in a lapping compound....
02-14-2012, 01:17 PM #10
Job/work piece description would be helpful...
If you are lapping a soft material you may wish to use a lapping compound that breaks down with use, so as not to continue lapping...
Bon Ami cleanser springs to mind.
02-14-2012, 03:00 PM #11
My shop is connected to a place called Covington engineering. They sell all kinds of lapidary supplies from graded carbide to aluminum oxide. Depending on what is is you are lapping and how fine a finish you need you could even step up to a cerium or super cerium paste.