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I picked up the aforementioned sander off E-Bay but the seller didn't have any documentation with it. The drive belt was only 11" wide and he explained that it took a while to get it adjsted correctly. So, I buy a new belt, which came today and I put the thing on. I didnt want to over tighten it so I set the adjusters up until it would pull a 15" wide chunck of plywood through taking a 1/8 turn cut with 36 grit at full speed. No matter how I adjust this thing the belt keeps walking toward the motor side of the rollers. I measured to make sure the rollers were parallel, I tightened and loosened both adjusters, I even pulled the belt back off and turned it around. The belt keeps walking toward the motor.
So, what little trick am I missing here?

Steve you need to tighten the belt on the motor side while loosening the outboard side. In effect you want to cock the inside or motor side so that it is longer than the outboard side. This will shift the belt towards the outboard side. The trick with these machines is "A little bit goes a long way" If your looking for instant results you will surely overcompensate. 1/8 to 1/4 turn at a time and then wait while the belt runs and shifts over. Takes a while and sometimes a lot of tries. You can download the manual at http://www.wmhtoolgroup.com/

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The 10-20 is impossible to adjust the belt to run centered too, at least for me, but there is an advantage to it not running centered.

When I center the belt it does stay that way for a few passes but when double pass sanding (turning the joined top or back around and doing the other side) the infamous little ridge develops. When I just let the stinkin belt live where it will, on the motor side......, the ridge goes away because the belt is not pressing up on the wood under the outboard end of the drum.

In addition - Performax made a mod to these machines because of the poor belt tracking and that is the addition of white plastic/nylon guides under the feed belt that help guide the belt from running off the ends. Older machines don't have these guides and probably do not track as poorly as well......

As for live and let live meaning leave the belt on the motor side I have not worn out a belt yet after about 10 guitars with this machine.

BTW why the 36 grit? I have some but I am saving it for Billy's face........

Those feed tables SUCK!!!!!

Good luck, and let me know if you ever get it working. I'm currently trying to rebuild mine, re-engineering about every component except for the table bed itself. I've tried about everything from turning crown in to the rollers, to making new heavy duty tension adjusters, to moving the motor to the other side of the drum, flipping the belt around backward, you name it. No matter what, where, or how much you adjust, it always tracks right over to the motor.

The manufacturers apparently never actually figured it out either, because their solution has been to put some ceramic guides at the edges to stop it from walking off. Kind of a cheap fix, and still wears out belts, but better than nothing I guess. My next step is to try a flexible shaft coupling from the motor to drive roller. I have no idea it if will help, but my motor does wobble a bit and some misalignment may be contributing I suppose. If that and another new belt doesn't cut it, I guess I try to rebuild my table with 2" or 3" rollers that don't flex as much. I think it's just a bad design.

Edit: - didn't see Hesh's post. I guess they use nylon, instead of ceramic guides as I thought. Mine is a really really old 22-44 by the way.

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Thanks guys, I'll give a go. And thanks for the link, Bob. That was my next search.
Hesh, I've got one guide block under there on the motor side. I wouldn't mind if the belt ran on one side or the other, but this one is pressing to hard and starting to fray. I loosen it all up, slide it back to center and repeated the process about five times. The 36 is on there to flatten some cabinet door panels. I would normally use the planer to do this job but thought it would be a good opportunity to set up the sander since they have to be taken down to 1/2".

Steve

Thanks Steve!

David you know you could try using an apprentice as a carrier board and sending him/her through the machine and seeing what happens.......

The drive belts work great with the right belt. Several years ago I had the same problem with the belt not tracking properly. I had purchased the new drive belt from an eBay supplier (actually three). That is when the trouble started. I adjusted and adjusted and it would never stay centered. Finally, I called Performax and one of the Performax technicians finally asked me if I was using a Performax branded belt. When I said no he said that was the problem. The belts are touchy and the Performax belts take it into account. On his advice I bought a Performax branded belt, installed it, and it has tracked perfectly for the past two years. So the point of this post is to let everyone know that this can be a problem if you are using an aftermarket (cheaper) belt!

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Sylvan
http://www.wellsguitars.com

I don't think my problem is belt related, because the problem seems consistent with the table and not the belt. I use Klingspor belts, and when flip the belt around 180 degrees, it still tracks toward the motor just as fast. Seems like if there were any inconsistency in the belt it would consistently track to the bad side of the belt, but it appears indifferent in my case.

Sylvan, are you taking about using one of their poly belts, or a standard sandpaper one. If going to a poly belt is the answer, then I'd probably just build a new table that wasn't so sensitive, because I can't justify spending $600+ to replace belts on a $500 machine.

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I had both a 10-20 and a 16-32 both came out of the box just fine and gave me no issues till about 30 or 40 hrs of use. the 16-32 needs adjustment about every 50 times I use it the 10-20 i adjusted one time and ran straight from then on until it was stolen last month. but it was used only for final sanding and very light cuts.

Any direct drive belted conveyer system will need adjusting from time to time. First off a new belt is not a perfect loop it is built to an expectable tolerance in length and concentric. After market belts tend to be made with loser tolerances than OEM belts. Also the belt stretches over time and use and will stretch even or on evenly depending on how well the setup is preformed. If you add too much tension to the belt the it will tend to stretch unevenly and will need concentric adjustment more often and will ware on the bushings in the pulleys. You adjust this type of system by increasing the tension to account for the length tolerance and stretch and you adjust the alignment of the motor drive pulley and the outlet pulley to each other to account for concentric issues.

Did you get the infeed/outfeed tables with it? When I bought mine off a friend, two things I didn't do - install the tables, and install the ceramic guides under the table. While I didn't really have a problem with belt drift, it still moved.

End of story - install both ceramic guides, and the tables.

Scratch that - I now have the poly belt (about $200 at the time), and they work SO much better, completely different machine (and I liked it to begin with, once I got the dust collection squared away).

Mine has a serial number under 2000, and came from when it was a man and his wife making them in their garage I believe. It was originally made to mount on a radial arm saw, but has been modified and heavily reinforced with a dedicated stand and motor. So no, I don't have any guide blocks. I do have the infeed and outfeed tables though, but it doesn't matter. I can take the table completely off the machine, and the belt will walk from the outside to the inside in less than 4 or 5 cycles of the belt. Same with a new belt or old one, and walks to the same side whether the belt is flipped forward or backward. I have it apart right now, and a new flexible drive coupling should be here by the weekend. I've mic'd out the rollers, and actually recrowned them, set the table up with 40" digital calipers, it doesn't matter. I can it spread it tight, loose, adjust either side in or out, and it always walks in to the motor.

I think part of the problem is that it relies on 23_1/2" spindles that are under an inch thick and flex inward at the center. I've considered making some adjustable rollers to support the center outward. That or perhaps somehow even a slight misalignment at the motor can cause a strange tug in toward the motor, though that doesn't entirely jive with me either. Still, I'm going to try the flexible coupling, a new belt, and if it still doesn't work I may just rebuild the table with 2" or 3" (which it should probably have anyway). It's a pretty crude machine anyway though, and if I actually used it much I would think about dumping it and getting something better. I'll probably try to milk this one for a while longer though.

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Eschew obfuscation, espouse elucidation.