"Robin S." wrote in message
. ..
snip---

Do you have specific pointers on how to do this? I don't specifically have
a
need to know, but I'm sure other would appreciate some insight.

Things like using a stone vs. emery cloth/paper, grits, SFPM, and hand
technique. Sounds like a neat trick.

Regards,

Robin


I've always taken advantage of the highest spindle speed available to me,
secure in the knowledge that grinding demands high surface speed. The
faster the surface speed, the better (and faster) abrasives perform.
Heating, naturally, is a problem.

Typical procedure for me has been to machine to roughly .0005" oversize,
then polish for size and finish. Constant cooling and measuring is required
when shooting for a tight tolerance. Seal and bearing fits are a good
example of where I use this process.

Grits? Depends on how much is to be removed and the finish
required/desired. I've used as coarse as 60 and as fine as 600.
Regardless of where you start, though, it's smart to use them progressively,
which eliminates polished surfaces with scratches.

What works very best is strip, which you hold by the ends. You can spot
polish by using an edge, but care must be exercised, otherwise it's easy to
create undercuts. You also must learn to avoid edges, which are easily
rounded off. Short turns are very difficult for that reason. I must
confess, the majority of the polishing I've done has been on soft materials
(anything machinable, not requiring a grinder). With rare exception, I've
had the use of precision grinders for hardened work. Still, the principles
are the same, it just takes a little longer.

It's easy for strip to get wound around a spinning object, so care must be
exercised to avoid wrapping well enough for the strip to do so. Keeping the
ends apart helps avoid problems. If you find you're applying pressure at
the part with fingers instead of holding the ends, the strip is inclined to
wrap around, dragging your fingers in with it. Be careful. Never permit
the strip to complete a circle.

I never use files, which make it easy to lose roundness, and are generally
too aggressive for fine work when the part is spinning. I've always avoided
using anything rigid (stones, for example), with one exception. I ground
a set of stepped plug gages for a defense installation, but had to use a
tool post grinder. There was no precision grinder in that particular
facility. I ground the diameters on top tolerance, then followed up with
polishing cloth, quite fine, and placed between a pair of parallels. My
purpose was strictly to bring up the finish, which, typical of a tool post
grinder, wasn't very good. It took only a tenth or so to enhance the
finish. The parts had a lapped appearance. To be perfectly honest, I was
surprised, and impressed.

Not much guidance, I realize. I think each of us develop what works for
us------which is what I did. I don't recall anyone training me to achieve
the end result in the way I do.

Incidentally, parts so created will pass extensive inspection procedures.
It's not a hack way to go, not if applied well. .

Good luck!

Harold