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Clean Up Before Powder Coat

Discussion in 'The Garage' started by Limpy, Apr 6, 2012.

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  1. Limpy

    Limpy XS650 Enthusiast

    I am building my first bike, a tracker from a 1980 Special. I have disassembled down to the frame and cut off all of the pieces you all (and Omar) told me to. I listened to you and used an angle grinder and 1/8th inch cutting wheels and 40 and 80 grit flappy flappy flappy wheels. That all worked great.

    By the way, I weighed the naked frame - no swing arm - before surgery 53 pounds and after 44 pounds. To verify I weighed the pile of parts at 8 pounds, the last pound is black dust all over my garage.

    How much do I need to clean up the grind marks before powder coat?

    I have been using 120 grit long strips of sand paper and cleaned it up pretty well. There are a lot of crappy welds that I won't spend much time on. I realize the really visible areas need to be clean but there are a lot of areas that may not need so much time. I intend to powder coat in light to medium grey flat finish to mask some of the imperfections. (Is there a color that masks the imperfections of the rider?!?)

    I know you guys hassle newbies for not posting pictures so here are a couple. I bought the bike in May 2011, the first pic is December 2011 just before I started tear down. Before you say it, the lunch box on the back came off the first day and was just set here for the picture. Note the work table, you guys showed me how to make that too. The second pic was a few minutes ago and the last is the front right down tube. I polished it with a strip of 120 paper like a shoe shine. The black paint that still shows are weld imperfections.
     

    Attached Files:

  2. I use brass to smooth out discrepancies after grinding when I'm doing a clean up. Then finish up with rotary files and flap sanders. frame 013.jpg frame 009.jpg
     
  3. They make a product called "LAB METAL or METAL LAB" that you can use as a bondo/filler that will take powdercoat, also JB WELD supposedly takes powdercoat. I have used the first product and works GREAT, not so sure about the JB WELD though.
     
  4. Pov76

    Pov76 XS650 Addict

    I've used silicon bronze

    Posted via Mobile
     
  5. Poverty

    Poverty XS650 Addict

    Not to thread jack .. but if your not going to powder coat can you just use bondo/ spot glazing putty or something similar ?
     
  6. Limpy

    Limpy XS650 Enthusiast

    As I understand you can use body filler and paint, but not powder coat. The 400 degree temp for powder coat limits the options. I just did a Google search on this and found a number of metal based fillers that are mentioned by powder coat people. I think what I am going to do is use JB Weld, which was mentioned a number of times, since I am only filling small spaces.

    Thanks everyone for the input.
     
  7. RFLIVES

    RFLIVES Resident Sidecar nut

    Use lab metal works great
     
  8. justin

    justin XS Monger

    Jb weld only holds up in small sections, and you have to use the "real" stuff. Not the JB quick. Lab metal works alright as well in thin layers, but both will lift in thick layers. Call the powder shop your taking it to, they will let you know what to use, and most likely will have a preference. Myself personally, i wouldn't use jb weld. It tends to discolor the powder and lift more than not.

    If the grind marks aren't that deep, your powdercoater can use a fill in primer powder first. then you can sand it all smooth. Also flat colors really don't hide imperfections, in some cases it makes them worse. Cheapest way to hide imperfections is to not have any :D When im powdercoating an old frame, ill use the filler primer, sand it smooth, hit it with my color, wet sand, then hit it with a nice low temp clear. You can also swap out the gloss clear for a matte gloss as well if that's what your after.
     
  9. olddude13

    olddude13 tracker dude

    Limpy, die grind most of the paint out and mig weld then grind/sand/smooth
     
  10. 59Tebo

    59Tebo 59Tebo Top Contributor

    For those of us without our own welders: how about the old fashion (pre-Bondo) method of (solder) lead-filling? Sure, it'd have to be acid core (to "stick"), but if resin core solder conducts electricity everywhere else in the universe, wouldn't the acid core solder conduct likewise to do a proper powder coating job? I'm thinking of this on the frame to touch up all the wonderful factory welding, and where I'll be grinding off the 'un-needed' parts. These will not be structural, just cosmetic...
     
  11. jd750ace

    jd750ace Front Toward Enemy

    The pros use braizing rod, as mentioned twice above, to fill and smooth. The ultimate to me is to have the welding be so pretty you don't want to cover it up, but since that's were you are, that's what I say.
    As far as fillers, have your PC guy tell you what he will warrant coating over, plain and simple. If you put something in there he does not want to cover, he can't be expected to stand liable for it letting go on the bake, or seperation/cracking afterward.
     

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