thunking combination belt/disc sander

I have one of those ubiquitous 36" belt/6" disc sanders. I've put a lot of miles on it.
It's starting to develop a really horrible vibration problem. Used to be, I wouldn't bother putting on my ears just to run this machine by itself. Now it has become quite obnoxiously loud.
It sounds like it's binding, building up some tension on the belt, and then releasing it with a loud, hollow THUNK. I can see the powered roller jolting in time to the thunking.
Obviously, something's out of whack, and I need to figure out what before the poor thing shakes itself to pieces. I tried to take the machine apart, but failed to get the disc off, and that was as far as I could get. I removed the set screw and even resorted to prying on it a little with some suitable probe, but it's stuck fast, and there's nothing but the plastic shield to pry against. I don't want to damage my machine, and there's nothing useful in the manual to give me insight here.
Has anyone encountered the thunking problem? What was it?
Does anyone have any handy dandy tricks for getting the sanding disc off? I just put on a new piece of sandpaper not too long ago, and so I haven't yet resorted to pulling it off. I don't remember there being anything to find under the adhesive disc other than a featureless machined surface.
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Michael McIntyre ---- Silvan < snipped-for-privacy@users.sourceforge.net>
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'Silvan' Think . . . "BEARINGS". Either the motor itself, or more likely the bearings that support the 'Drive Roller' and/or the 'Idler Roller'. {IF it's one . . . replace them ALL}
Re - the sanding disk . . . get a hair dryer {I 'rescued' one my wife through out . . . women with long hair 'kill' them rather regularly}. Play it across the disk, on the 'Lo' or 'Warm' setting. As it warms up, begin peeling the old disk off. Keep the warm air going.
A couple of tricks . . . if the disk is still good, 'sandwich' it between a couple of pieces of wax paper . . . use the same warming trick on the platen when re-applying the a new PSA disk, or Disk Cement if using a 'dry' sanding disk.
Regards & Good Luck, Ron Magen Backyard Boatshop

SNIP
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Bearings. Had the same thing happen to a Griz sander. Change out those bearings NOW!!!.

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It's too late. Change out those bearings and sanding belt drive pully.

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Unscrew it from the table and turn it over. Mine did the same and I tightened the belt and it diminished. Sounded like something was out of round on mine. Do not advise removing the disk if at all possible. After loosening mine it refuses to stay put. the Set screw on the side of the back of the disk is a bear to keep tight in the aluminum disk. Even with blue loc-tite. Look down behind the disk while slowly rotating it and you can see the set screw. I made a mark on the perimeter of the disk so I can find the set screw easier.
Silvan wrote:

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Gerald Ross
Cochran, GA
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[...]
Teethet belts are usually made to order, nut you should take the old one to any decent transmission belt vendor (usually combined with a ball-bearing store), which should exist in any respectable city and can even vbe found in smnall country towns; at least in Germany, in the US it should be also possible to locate one if the BORG have not assimilated all...
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Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
mailto: snipped-for-privacy@physik.uni-bonn.de Phone: +49 228 73 2447 FAX ... 7869
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[...]
Toothed belts are usually made to order, but you should take the old one to any decent transmission belt vendor (usually combined with a ball-bearing store), which should exist in any respectable city and can even vbe found in smnall country towns; at least in Germany, in the US it should be also possible to locate one if the BORG have not assimilated all...
--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
mailto: snipped-for-privacy@physik.uni-bonn.de Phone: +49 228 73 2447 FAX ... 7869
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This may be a good place to try a link belt. It can be installed and removed without taking the machine apart and might stop the clunking induced by the "set" in the belt shape. Just a thought.
Silvan wrote:

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Gerald Ross
Cochran, GA
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Gerald Ross wrote:

I'm open to anything up to an including braided horse hair or cat whiskers. I just want to get the machine back up.
Delta hasn't answered my email. Nobody lists a suitable belt in an online inventory system. I'm just coming up completely empty here, which is somewhat baffling because there are millions of these machines in use every day.
For one thing, I've never seen a link belt for sale anywhere, except those intended to be used on cars for emergency repairs (and I haven't seen one of those in years.) For another, I've never seen them anywhere close to narrow enough for this application.
Where can I buy a 3/8" wide link belt, and would the teeth on the pulleys be a problem?
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Lee valley, Woodworkers Supply, Grizzly, every other woodworking supply I know has it.
On Tue, 02 Sep 2003 17:47:19 -0400, Silvan

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http://www.paragoncode.com/shop/link_belts/ has a nice little write up on this very subject with complete links to the big two suppliers.

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I had one develop those symptoms before the bearings completely locked up. I replaced it with a 6x48/12 sander. There is nothing under the disc on mine but a flat plate. The plate is keyed to the motor shaft and held in place with a set screw. Someone may have used Loctite on the set screw or shaft. GENTLE tapping from the shaft side may loosen it. Or you might try heating it with a heat gun [or your wife's blow dryer]. harrym
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