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  • question about polishing technique- aluminum

    hi fellas- i was wondering more about "cutting and "coloring"....and would like to "pick some brains"!

    Do you guys use color strokes during each stage? say, initial cutting, polishing and then buffing? i'm trying all kinds of "procedures"! I'm close to getting one that works for me. but sometimes its less than desirable.

    If you end each stage with coloring...i'm thinking it will make the next stage a bit easier to polish? Thank you

  • #2
    Re: question about polishing technique- aluminum

    I don't know what cutting and coloring mean, although over the years I have heard the terms thrown around a lot. It looks to me that all compounds cut, and the color of the metal is the color of the metal. I'll tell you what I do.

    Usually I pass the piece over the wheel against the direction of rotation, and then pass it directly back to where I began the pass but with a bit less pressure. That move lifts all of the compound off of the piece and puts it back on the wheel. Then I move over and do it again. If it seems that I am accumulating too much heat in one place I will change places and let the other place cool off a little. (I polish a lot of sheet metal and heat shrinks metal, causing it to warp.)

    Richard

    If the piece is a tube or a rod or some other shape on which this is not practical, I just do what I can.

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    • #3
      Re: question about polishing technique- aluminum

      Originally posted by blinddog View Post
      Do you guys use color strokes during each stage? say, initial cutting, polishing and then buffing? i'm trying all kinds of "procedures"! I'm close to getting one that works for me. but sometimes its less than desirable. If you end each stage with coloring...i'm thinking it will make the next stage a bit easier to polish? Thank you
      I normally use pneumatic die grinders so will go "back and forth" watching until scratches that weren't just made disappear. Then I sweep across with the rotation of the wheel. I like have the tool in my hand because I can watch the buff's action in the reflection of light. I ended up converting a sawzall to run my buffs and it works fantastically: controllable speed with amazing reserves of torque at any moment.

      You'll develop your own technique that works nearly always for you. Unless a problematic part comes your way with the sole purpose of teaching you a lesson... (I'm about to make a new thread)

      Chris

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      • #4
        Re: question about polishing technique- aluminum

        Chris,

        Post a photo of your sawzall machine.

        Richard

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        • #5
          Re: question about polishing technique- aluminum

          Sawzall is a Hitachi from Lowe's for $79...
          Click image for larger version

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          This model seemed the easiest among all to separate the motor from the front. It also has variable speed. I removed the black rubber cover and didn't bother to replace it. The variable speed handle I believe has four positions; but it allows amazing control of torque and RPM.

          The motor axis is more or less in-line with the sawblade area. It's output is geared down to the lower shaft, which fortuitously comes with a hole in the housing for my output shaft. The Hitachi incorporates two bearings on that shaft. I pressed the driven gear off the shaft and the output side has a sleeve for the bearing that conveniently has an inside diameter that is a light press fit onto a 1/4" shaft. I turned a piece of aluminum to hold the gear and the motor-side bearing. It has a letter C or letter D bore size (interference fit onto a 1/4" shaft). The output shaft I used is a 18" or 20" stainless steel round bar I got from a metal supplier.

          It took me longer to choose how to modify this sawzall than to actually modify it once I made up my mind.


          Click image for larger version

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          At the buff end is a length of 1/2" round aluminum bar. One end is drilled letter C and the other is threaded 1/4-20 and the C end was pressed onto the stainless rod. Then I have spacers which fit each size of buff I'm using (1", 5/8", 1/2", etc) and use different length 1/4-20 screws and flat washers to clamp the buff to the shaft.

          Along the shaft, for the handle, is a 1/2" ID wheel bearing pressed into a short sleeve. The sleeve is threaded to accept the handle. I initially used a plastic handle from an angle grinder but it vibrated too much, so I got some 7/8" aluminum round and put a motorcycle handlebar grip on it. This is visible in the pic somewhat close to the buff, but is useful at nearly any place along the shaft. I can also use the tool without the handle for low-load applications, tucking the sawzall to the left of my waist and letting the buff itself bear the balance of the weight. When I do this, I move the handle to the protruding area that houses the saw's action. While I could remove that excess material, it proves useful when I want to rest the sawzall on my knee or thigh to support the tool. So I'll leave it be. Technically, there are no permanent modifications to the saw. It is almost like Hitachi intended this tool to be "hacked" for other uses.

          The stainless rod is amazingly robust. I have put a 2 to 3" bend on it when leaning into the buff with at least 40 pounds of force on the bearing handle and it stays true. The bearing in the handle is 2x the size of the rod so it can slip up or down freely. I believe I use this tool in a video I made regarding a part that's giving me troubles: https://youtu.be/7AdXyMTEOks

          I have probably 40 hours of use on this sawzall and it is incredible. After a 4 or 5 hour session, the motor area is barely warm. It feels like this was well engineered for the power requirement of reciprocating saw action ... and that using the spinning output shaft buffing usage is much less demand.

          Things I'd do differently if I made another one:
          » Make the threaded end of the output shaft out of steel or stainless as the aluminum has needed trimming once or twice because the force I put on the buff and shaft caused the bolt to bend and deform the threads.
          » Tool dip the bearing sleeve on the travelling handle for the rare moment you forget and make it hit the edge of your work.
          » Use a coupling and 2 pieces of stainless rod for the output shaft so the whole tool isn't 3 feet long.

          Thanks,
          Chris
          Last edited by unexpectedly; 04-28-2015, 01:31 AM.

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          • #6
            Re: question about polishing technique- aluminum

            Very great. Thank you.

            Richard

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