oldjag wrote:

Just got a Boyar Schultz 6" x 12" grinder for the home shop. It seems
grind pretty square for an $200 old machine, ie. two sides of a bar
within 0.0002 over 4", but the surface is a little wavy looking. The
spindle is tight, but there is about 5 degrees of backlash between the
motor shaft and the spindle shaft. I think it's direct drive with some
kind of toothed coupling between the motor shaft and the spindle. The
3/4 hp 3 ph. motor looks original. Maybe this coupling is effecting
the finish? I did a google on Boyar Schultz but no response. I guess
they are no longer in the grinder business...anyone have a manual for
this machine or parts info? Also I plan on grinding valve shims for
the Jag DOHC engine, these are ~1/2" diam, 0.080 to 0.100" thick. I'm
thinking they can go right on the magnetic chuck, with perhaps some
kind of a "backstop" to keep them from flying - any suggestions?

Let me preface this by saying that I do not (yet) have a surface
grinder. I do recall reading somewhere that the surface finish from a
grinder with a 3ph motor can be affected by poor 3ph power as in from an
unbalanced rotary converter. The developed leg gives a "lumpy" torque
profile which is reflected in vibrations and surface finish. A good
quality VFD should provide clean power.

Pete C.