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  1. #1
    scott.livesey is offline Plastic
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    Sep 2011
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    sanford, nc
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    Question 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.
    Thanks,
    the old sailor

  2. #2
    technocrat is offline Aluminum
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    Oz
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    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.

  3. #3
    i_r_machinist is offline Titanium
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    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.
    have fun
    i_r_

  4. #4
    wrenchhead531's Avatar
    wrenchhead531 is offline Aluminum
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    Fayetteville,AR
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    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

  5. #5
    wrenchhead531's Avatar
    wrenchhead531 is offline Aluminum
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    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

  6. #6
    gmatov is offline Diamond
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    SW PA
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    Scott,
    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.
    George

  7. #7
    RC99's Avatar
    RC99 is offline Titanium
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    near Rockhampton, Queensland, Australia
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    I use the garnet grit used for sandblasting for very coarse lapping... Makes stones flat in no time when rubbed against glass..

  8. #8
    Timw is offline Stainless
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    Nov 2005
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    N E Florida
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    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.

  9. #9
    Zonko is offline Stainless
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    Aug 2011
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    Northern Germany
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    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....

  10. #10
    Armenius is offline Cast Iron
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    Jan 2008
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    S-W Ontario
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    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.

    Arminius

  11. #11
    VertigoGlass is offline Aluminum
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    Jan 2012
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    San Bernardino Ca
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    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.

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