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Suggestion for thin stainless trim polishing

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  • Suggestion for thin stainless trim polishing

    I'm trying to polish very thin (around 3 mm ) stainless trim. I have all kind of sanding papers, wheels and compounds. But I couldn't find to true recipe yet. Here is the trim before sanding and polishing. As seen it's quite good surface.

    Click image for larger version

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    And here is after my procedure.(800 > 1500 > 2000 > cotton wheel and compound > soft cotton wheel and compound). It's worse than before. You can see the scratch by coton wheels.

    Click image for larger version

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    But, I want to see really perfect shiny surface and learn to where did I wrong.

    1) My wheels around 500 mm diameter. What should be my wheels speed for polishing and mirror finish? ( rpm)
    2) Pressure should be hard or soft?
    3) If the material is heating while polishing, is it advantage or disadvantage?
    4) Should I use more compound or less compound on coton wheels?
    5) What kind of wheels should I use for don't scratch the surface?
    6)Or how can I remove that lines?
    7)Or what is your recipe for this stainless trim?

    Thanks.

  • #2
    One thing you did not say is what compound you used. And I don't mean just the color. People say sometimes, "I used a green stainless compound." Well, there are at least a hundred different green stainless compounds available, all the way from very coarse to very fine.

    And did you sand by hand, or with a machine?

    Are you sure your wheels are 500 mm? That is a huge wheel.

    If your trim piece was actually in good enough condition to begin with 800 grit, you could have just used a standard medium stainless compound instead. I typically sand stainless up to 600 grit and then use compounds on cotton wheels.

    I suspect that your problem is that you did not sand thoroughly. Stainless is very hard to sand. It takes much more work than people imagine. When you sanded with 800 grit, you covered your piece with 800 grit scratches. To move up directly to 1500 from 800 is a huge jump. You probably left a lot of 800 grit scratches in the piece that weren't visible until you buffed it with the compound and made it shiny. I would sand it well with the 800 and then go at it with the compound on a hard sewn wheel. A soft wheel will not cut stainless. A hard sewn wheel has the spiral stitches somewhere between 6 and 8 mm apart.

    I would never use more than 800 grit paper on metal I am going to polish. I use a medium grit aluminum oxide compound after that, on a hard sewn cotton wheel, and then a fine aluminum oxide compound after that.

    Too much compound provides lubrication instead of cutting. It's better to have too little. If I pull my piece against the direction of the wheel and then move it back to where I began and there is any compound remaining on the piece, I know I have too much compound on the wheel. You want it to get hot, but not hot enough to warp the trim piece. If it is uncomfortable to hold in your bare hand it is getting too hot.

    To get that final mirror polish I use a mildly abrasive liquid polish on a clean microfiber cloth. (And I mean really clean. Wash your new cloths. They sometimes come from the textile mill with grit in them.)

    Richard

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