"Charles A. Sherwood" wrote in message
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New wheels come with cheap plastic centers so its difficult to get
them mounted concentric in the first place. Might not be a problem
with small wheels but it doesn't take much on a 10 inch wheel to make
the whole grinder vibrate. I think that lead use to be the prefered
material for adapting the large hole in the grinding wheel to the
smaller grinder shaft. Should I replace the cheap plastic spacers
with something better?

If you find the plastic permits the wheel to move about too much, that
wouldn't be a bad idea, but use good sense. There are issues with the
spacers that are critical, which explains why they're sloppy. They may not
work perfectly that way, but they're safe. If you make your spacers too
tight, and the bore of the wheel isn't at a perfect right angle to the wheel
face, it's possible to fracture the wheel when you tighten the nuts. The
snug fit would limit the wheel's ability to square with the flanges, which
it will do, either by cracking the wheel, or compressing what ever is in the
way.

I am using the standard flanges and blotters supplied with the wheels.
I did not tighten the wheels very hard because they ususally tighten
themselves up pretty tight. A 1.5HP motor accelerates pretty rapidly
and the 10 inch wheels have a lot of mass so I suspect the motor
tightened them up very tight by now.

On the outside chance that isn't happening, check how tightly they are
held. If the nut had crud in the threads, it's possible it's not turning
freely, so it feels tight but it isn't. Long shot, yes, but worth a look.
Be certain that the nut runs freely, all the way until it hits the flange,
otherwise you have no clue if you're tightening the wheel, or fighting the
dirty thread. Your flanges should be imprinting the blotters. If you
see signs of the wheel sliding about, with smudges on the blotters instead
of imprints, you're not tight enough. The blotter should appear clean, but
compressed.

I suspect I'm using too much pressure on the dressers and not the
light touch that harold recommends.

It has been my experience that once a wheel starts bouncing, it encourages
itself. Especially if you have no fixed reference, when you try to reduce
the runout, all you do is make the wheel smaller. If you think you can
simply hold the dresser of choice against the wheel and improve it, you'll
be disappointed endlessly. You have to work smart at reducing the runout,
which means to take it off a little at a time, such that the bounce of the
wheel isn't transmitted into the dressing device. A light touch usually
solves that riddle, along with taking a narrow approach. Don't use the flat
face of a dressing stick, but a corner instead, where the amount in contact
is minimized. Once you get a spot running true, you can usually move out
and improve the immediate areas. It's not rocket science, but it does
require a little thought. Surely you've already noticed how the bouncing
wheel sets up a pattern that tends to repeat. You have to break the cycle.

This grinder was purchased used and the original 10 inch wheels were
worn down to about 7 inchs. It ran fine with the old wheels.

Perhaps I should remove one wheel to reduce the vibration and dress
the remaining wheel. After I get it running smoothly I can then
add the second wheel and dress it.

Unless you ended up with some very poor quality wheels, there's no reason to
not expect new wheels to run smoothly once dressed. If that's what it
takes, then that's what you should do. Just be certain that all your
efforts are when the wheels are at operating speed, and don't discount the
possibility that the wheel sides may not be parallel. That would certainly
yield a heavy side, and would be corrected only by dressing the sides of the
wheel. I often dress the sides with a diamond, strictly for balance, right
down to the blotter. It often improves how a wheel runs.

Harold