Hmmm..interesting. Every thing I do is UHMW and at least 2" thick so it
may change things a bit. I can get a fairly good finish reaming but the
size is always out a few thou and any chips roller under the cutter the
finish is shot. With the right feed and speed I can get what feels like
a glass smooth finish boring that is dead on..using a not-too-sharp
carbide indexable bit on the boring bar. The last boring pass needs to
be greater than 1/16 so there is something to bite.

Fortunately, most of the tolerance I need to hold are +.005 and the
finish can be "good enough". I'll try reaming with your method of
taking nothing off but the fuzz just to see what happens.

Koz

GMasterman wrote:

Boreing has not produced the finish that I am looking for. Looks like the poly
is soft enough tat it springs back after the boring bar passes, leaving a rough
surface. I have made many smaller bushings, bored or drilled, then reamed to
end up with a slick finish that I could not produce any other way. I drill with
a 3/4" drill bit, then ream to 0.750 and it comes out perfict every time. Need
to reproduce the same results in 1". BTW, a fortsner bit yealds a better
surface that my indexable boring bar, but still not good enough to please me.
Thanks!