From your
description, it already sounds like I need to
start shopping for a bench grinder.
A grinder is way too fast for polishing plastic (unless you mind divots
and burns). Though it would be hand-held, you might want to try a buffer
first (much slower).
Actually, the crucial thing is the effective linear speed at the edge of the
polishing mop, the value of which is dependant on the material being
polished, and the polishing compound in use.
A secondary consideration is the cooling of the mop. A large mop spends less
time in contact with the work piece, so remains cooler during the polishing,
which is less likely to damage the work.
A look in the catalogues of the materials firms should show a suitable
polishing compound for thermo plastics, and the will often come in different
grades - cutting for rough work, and finishing for final buffing. A good UK
supplier is Cetelem.
My polishing set-up is made from an old double-ended, floor standing drum
sander, fitted with "false noses" - the tapered screws that hold the mops
(remeber you need a left hand and a right hand one for a double ended
machine!). It is run from a single phase 1/3 HP motor, with a three step
pulley to allow for speed changes (I ought to fit a varible speed drive, but
haven't found a cheap one yet). The floor standing base makes the unit nice
and stable.
If you start polishing, make sure you have suitable protective clothing
(goggles or face shield, leather apron, leather gauntlets, and dust mask),
as the mops have a habit of picking up any item you are holding, and
throwing it back at you! In the case of hard plastics (e.g. Bakelite),
beware of stress fractures in the material - I've had a radio case shatter
into razor sharp splinters - it took me hours to get them out of my arm
(hence the protective clothing...........).
Jim.
