Anyone want something powdercoated?

[vwdaun at yahoo.com (Daun Yeagley)]

--- Ron Pieper <rapieper@yahoo.com> wrote:

> Daun, Qs about powdercoating....
> 
> - how able are you to tape off areas that you don't want
> powdercoated?  i.e,. bearing bores,
> mating faces, threads, etc.?  Sometimes large parts of
> the piece.  What's the process?

I've taped off mating surfaces / threads / bearing races
with good 'ol masking tape.  At these temps though, it does
get a little gooey so you need to wipe the leftover residue
with some mineral spirits.  (Incidentally, it's FAR easier
to peel the masking tape while it's still warm, otherwise
it's a real b*tch to chisel off.)  I wouldn't  recommend
masking tape for large areas.  There is a special high-temp
tape but we've never used it.
 
> - how clean would something have to be?  meaning free of
> oils?

Yes.  I did the valve cover on my '86 awhile back.  First
was a trip to the parts washer and a bake dry.  Sandblasted
the paint and then coated it.  (IIRC)
 
> - suppose someone delivered you a few clean but not super
> sanitary cast aluminum or magnesium
> parts...meaning that surface dirt would be gone but
> staining would be there.  Combined, say,
> they'd be about as big as, oh...an 020 gearbox, for
> example.  If you didn't have any further
> cleaning to do, and I taped the areas off, what'd be a
> ballpark price for that?

Hard to say - we like to make sure everything is clean,
etch & alodine for corrosion protection, then coat.  If
there was a bit of oil residue still left in the metal,
when heated we've found that it will run and really screw
up the finish.  Clean it in your parts washer and we can
blast it here.  (Taping off areas for bearings etc.)
 
> - how hot does the oven get?  (wondering if parts were
> delivered with bearings still installed, if
> they'd potentially fall out due to the expansion.  This
> happens in the 400*F range, in my
> experience, FWIW).

Remove the bearings.  The temps are in the 350-400 range
and the grease in the bearings will run / screw up the
finish.
 
> - could one potentially have clean scrap seals installed
> for the powdercoating, then later remove
> them so the bores would be pretty and shiny?  Or might
> the seals melt?  (see above question).

Again, if they were perfectly oil free, then maybe - but
can they take that kind of heat?
 
> What'd be really cool if if I had all my preload shims
> installed, and the gearbox otherwise ready
> to assemble, and gave it to you, then could pretty much
> proceed with assembly directly afterward. 
> Thoughts?

It's best to have things completely disassembled for
coating, period.  We've done several sets of airplane
wheels and had the bearings etc removed while coating them.

Any more questions just fire away...


Daun Yeagley - Wilmington Ohio
'80 Scirocco                 '81 Scirocco S 16v to be?
'86 Scirocco 8v              '88 Scirocco 16v 
'88 Scirocco Slegato (Gino!) '96 Passat GLX Wagon
'56 Cessna 172
The first rule of intelligent tinkering is to save all the parts - Ehrlich's Law.


 
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