In article ,
Harold and Susan Vordos wrote:
"Charles A. Sherwood" wrote in message
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[ ... ]
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.
The simple way to do this is to grip both wheels, and try
(without too much force) to advance one beyond the other, and then the
other way. Too much force, and you wind up actually loosening the nut
on whichever side is moving forwards, but light pressure should tell you
whether one is slipping.
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.
And also -- some flanges are rather poor shapes. Your machine
ran well with the older wheels, so this probably is not the problem, but
if it is, use your lathe to turn up a pair of flanges which are true on
both sides. Be sure to relieve the face except for perhaps 1/4" or so
at the outside diameter, which is where you want it to grip.
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.
What I've done to true a wheel is to put a stop sleeve on a
long-handled diamond dresser, (assuming that the tool rest has a clean
outer edge), and adjust so it just barely takes something off the wheel,
pass it back and forth until it stops spitting, then adjust it just a
little deeper and repeat, until you get a clean wheel the whole way
around. Repeat with the other wheel, and once both are balanced, you
can then use your dressing stone to open up the wheels which are too
smooth thanks to the diamond.
I've done this using parallel machinists' clamps, but I really
should take the time to make a collar on the lathe for the task. It
could even be a two-piece one which would let you make fine adjustments
as to depth once you started truing.
Hmm ... to be sure that you get it all -- perhaps you could roll
a well-inked stamp pad on the wheel's surface, and use that as a visual
indication as to when it is all removed?
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.
Then the flanges are probably good -- unless someone took time
to try different orientations for the flanges until they got the best
running?
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.
Proably a good idea.
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.
Another thing which can throw a wheel well off balance is if it
was soaking in water or oil at one side or the other. This should not
be the case with new wheels, but who knows what may have happened. If
this is the case, the balance will slowly change as they dry out.
Good Luck,
DoN.
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