It will be very difficult (nearly impossible) to allow for chroming
thickness on anything that requires a few thousandths precision. The
processes used for the plating and prep are just not controlled that well. A
plated part can easily end up several thou over or under the pre-plated
dimension. I speak from some very bad expriences with bearing surfaces in
chromed motorcycle wheels. It will be best to work with your plater ahead of
time when designing the parts to see if he can mask off the critical
surfaces. And, if he agrees that he can mask the critical surfaces make sure
this ends up clearly on the work order. On aluminum in particular it is
possible to end up undersize because of an acid etching step during prep.
Otherwise you'll need to plan on grinding to the final dimensions after
plating.


"Jim" wrote in message
m...
I have two pieces that will eventually be chromed. One will be held
via a shoulder bolt and the other will have pressed in bushings.
Neither piece spins. they must rock back and forth at low speed and
very light load. Should I allow for chroming when I ream the holes or
ream them afterward. If afterward - how much material should I leave
or should I ream them to size and then ream them again after chroming.

Thanks
Jim