I use several different sizes of sanding belts on various machines. Most sanding belts are now made with a diagonal splice joint that is held together with a strong piece of special tape. However, the adhesive on the tape seems to age and become weak. As a result, the belt will come apart even when the sandpaper is still good. How can I repair the belts? Is there a special tape that can be used to join the diagonal splice again?
Years ago, the joints were made by removing the sanding grit for a short distance on the two ends of the belt. The ends were then glued together to make a lap joint. Removing the grit in the joint area kept the belt’s thickness uniform. The belt also had an arrow on it to show the travel direction when in use to avoid the lap joint being snagged. The cut end of the belt in the overlap joint had to be moving in the direction where it would not snag on the wood being sanded. – Henry D Berns
Tim Inman: There are adhesive bonding tapes available to help you do exactly what you are wanting done. They are made and sold for building and repairing abrasive sanding materials. You can also mend or make abrasive belts by this DIY method: Obtain some bias binding tape from a fabric store, or you can make your own. Then use CA adhesive to bind the bias binding tape to the cleaned edges of the sanding belt you want to make or repair. I have done this many times, and it works fine. Sometimes, I don’t even use the bias tape. I just clean up the fabric/fiber edges of the broken belt and reglue with CA or super glue.
The real question to me is whether it is actually worth doing. If you are trying to do this and make a living, it almost certainly isn’t. The cost of the materials and time to repair vs. the cost of just replacing the belt and going on will almost always come out in favor of replacing and using your time on the job instead of on shop maintenance.
There are times when one must do it, though. I have a specialty lathe in my shop that I call my “Bill Jones/Maytag/Rockwell Delta” lathe. It uses an infinitely variable speed controller clutch designed and promoted by the late ornamental turner and dean of the profession named Bill Jones. It is a wonderful tool, and it uses very, very old-school technology: a powdered leather belt that slips on a wooden pulley. Bill showed me how to make one. Maytag supplied a two-speed reversible electric motor, and Rockwell Delta supplied the basic lathe. I had to make the leather belt myself. It is joined with cotton string and held together with CA glue. I have used it for 25 years now, and it has only needed repair one time. You can do it – but should you?
Chris Marshall: A number of years ago, one of our Woodworker’s Journal readers faced the same conundrum you are, Henry, with his belt sander belts prematurely breaking at the seam. He surmised that it was humidity in his shop that was accelerating the problem of the binding glue failing at the taped joint. His solution is to store new and used belt sander belts in sealable freezer bags until he’s ready to use them. Keeping the belts as dry as possible seems to extend their lifespan. Consider giving this tip a try.