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Stripping paint from cast iron assembly with bronze bushings?

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  • Stripping paint from cast iron assembly with bronze bushings?

    Hi Folks -

    I have a cast iron assembly that I want to strip the paint off. It's the frame assembly from a lathe gearbox and there are a number of bronze bushings pressed into it. Normally my approach is to dunk the cast item into a tub of Zep Industrial Purple and come back later to a clean piece, with the paint having liquified and run right off the surface. In this case, the bronze items probably won't allow this approach, as the Sodium Hydroxide in the Zep will most likely attack them.

    Does anyone have any ideas as to what I might use that would be compatible and allow a soaking process to take the paint off? I could go at it with a bunch of cotton swabs and acetone and scrub the paint off that way, but it would be a tedious and very time intensive process (I already tried this actually).

    Thanks for any pointers.

    Thanks,
    Lewis

  • #2
    I used aircraft paint stripper to get the paint off my aluminum cased gear box. I replaced many of the bushings but ti did not seem to do anything to the ones I left alone.



    http://www.machinistweb.com/forum/showthread.php?t=993
    Andy

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    • #3
      Andy - thanks for the feedback. I've used that aircraft stripper in the past but when I went to get more of it, the cans were nowhere to be found. I got some "regulations are ruining things" tale from the lad at the auto body supply house. I suppose I could try on-line. I remember that it worked very well indeed and a quick wipe with mineral spirits after half hour and the surface was as clean as a whistle.

      When you replaced your bushings, does one have to bore them out, or ream them carefully to fit the shaft, or are they usually sized to be used off the shelf and pressed into the casting? I'm a newbie with these things so forgive what may be a dumb question.

      Thanks again,
      Lewis

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      • #4
        Carburetor cleaner should do the trick. It usually lifts most of the paint of the carb and does not bother any brass parts.
        Larry - west coast of Canada

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        • #5
          Permatex spray on gasket remover.
          Gene

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          • #6
            Brake fluid...

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            • #7
              Originally posted by LHC View Post
              Andy - thanks for the feedback. I've used that aircraft stripper in the past but when I went to get more of it, the cans were nowhere to be found. I got some "regulations are ruining things" tale from the lad at the auto body supply house. I suppose I could try on-line. I remember that it worked very well indeed and a quick wipe with mineral spirits after half hour and the surface was as clean as a whistle.

              When you replaced your bushings, does one have to bore them out, or ream them carefully to fit the shaft, or are they usually sized to be used off the shelf and pressed into the casting? I'm a newbie with these things so forgive what may be a dumb question.

              Thanks again,
              Lewis


              I was surprised to find out that my hardware store bought bushing set had every size bushing I needed for the gearbox and they all fit perfectly! The only thing I had to do was cut them in half to match the hole or gear depth. Only one bushing I ran a reamer threw because it was a snug fit but even a little light sanding would have done enough to have a great slip fit.

              Only that big leadscrew bushing was the only one I didn't replace because it was a nice fit yet. This was just a pic I took to show the bushings.

              Andy

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              • #8
                I've used Purple Power full strength - and that stuff is potent - several times on my rebuilds with bronze bushings with no sign of problems. (I clean the nasty part with the bushings not knowing it they are bad or not til they are clean enough to inspect, and when good show no effect of the cleaning)
                If everything seems to be going well, you have obviously overlooked something........

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                • #9
                  It depends a bit on what kind of paint it is - I'd start with ordinary paint thinners, and if that doesn't work, acetone.

                  The most aggressive stuff for getting paint off (in seconds) was methylene chloride - not only does it take paint off in whole sheets, it makes your hands lovely and clean :-)


                  Ian
                  All of the gear, no idea...

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                  • #10
                    None of the sodium hydroxide cleans on the consumer market will hurt the bronze.The over the counter consumer stuff isn't a high enough concentration to do that.It will strip the oil from oilite bearings however,but that just means they will need saturating with fresh oil before service.
                    I just need one more tool,just one!

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                    • #11
                      If your are not in a hair on fire hurry, place your painted article in a coffee can or 5 gallon pail and shlosh about a cup of lacquer thinner over them. Close the lid. Open the lid from time to time and baste the parts with the thinner in the bottom. Keep the lid closed and left the fumes do the work.

                      In a day or two the paint will swell up like soggy bread. Brush off the paint or push it off with a stick as it loosens. Sooner or later all paint will be off but it takes over-night to a day or two. Wash the parts in clean lacquer thinner to remove the last traces. Work quickly when the lid is open. If the thinner dries the paint will re-adhere weakly but enough to make it difficult to remove. Use nitrile gloves (they swell anyway) and work in a well ventillated area.

                      I prefer Jasco paint stripper for larger parts. Spread the gel on, allow the paint to soften and scrape it off into an old box. Two applications will reduce any paint system to goo and leave the part clean, bare, and ready for paint prep. This stuff is methyl cloride in a gel vehicle. It skins over to prevent solvent evaporation. It has about a 20 minute open time. If you take much longer, the solvent begins to evaporate

                      These are my favorite paint removal techniques that leave metal parts unaffected. Plastics and rubber will be affected so let that guide your selection.

                      An OA cutting torch is a great paint remover. The flame pre-heats and the oxy cutting jet flares off the combustable paint almost explosively. Work systematically with respect for label plates, thin areas, plated parts, fittings, etc that heating will affect. Any remaining paint residue will be dry gray ash easily brushed off. This has the advantage of cooking out oil but the disadvantage of being smokey - and a fire hazard: burning chunks of paint can fly ten feet. Use only on castings and metal parts having thickness. Sheet metal will warp and buckle.

                      None of these methods has an effect on bronze bushings or pressed together parts, nor do they cause galvanic corrosion. The solvents evaporate completely. The dry residue are safe for residential garbage.

                      Acqueous solution are second best in my estimation. If the formulation is sufficient to attack paint it's no longer safe for critters and its dry residues concetrates the chemicals that make it work. It's a gift that keeps on giving. I never use them for that reason.

                      Neither do I sand blast without a booth or use a high pressure washer. They scatter stuff around in a spreading cloud extending hundreds of feet downwind. Masking and post cleaning of any crevices part is a HUGE PITA.

                      Use simple cleaning processes that minimize waste disposal and contains residues.
                      Last edited by Forrest Addy; 05-28-2013, 04:58 PM.

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                      • #12
                        I never heard of anyone using bronze bushing to strip paint aha got you there read your title AHA yaH beaut, I got you there didn't I ? he ,he. Alistair
                        Please excuse my typing as I have a form of parkinsons disease

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