Repairing Broken Abrasive Belts

Sanding belts have a shelf life, and once the joint tape fails, it's not easy to fix. February 16, 2012

I have encountered a problem with joints in sanding belts. I suspect humidity has loosened the taped joint. Someone must have encountered this problem and found a method of repair. I would replace them, but I have about 50 that are affected, plus long wide belts on the edge sander that are bad. The joints appear to have been done with some kind of tape that resembles filament package tape.

Forum Responses
(Adhesive Forum)
From contributor S:
The tape used to splice belts is a very specialized adhesive that is shipped and stored in dry ice. The application process then requires the belt to cure for 24 hours. An off the shelf adhesive would not have the strength with the shear pressure on the seam.

How old are the belts? If these are not very old, your abrasive supplier should be willing to replace them. It isn't uncommon to have a bad batch from a factory. They may already have complaints on the lot you have. There are shelf life issues with abrasives, but it's usually a few years. Belts, especially, will have problems, especially under the conditions you describe. We've had belts for upwards of five years that have maintained their splice. They are not stored in an environmentally controlled environment, but they are kept in their cartons which protects slightly from the variations from a very rainy week to a dry week. Now if you are buying a no-name on the internet, all bets are off. You get what you pay for.

From contributor F:
If youíre buying belts in bulk they need to be stored in a dry, stable environment. Technically they have a shelf life. I wonder if you could send them to an abrasives company and have them repaired?

From contributor D:
I use fiber hockey tape and clean the inside of belt with 95% alcohol because it must be clean for adhesion. Let it dry and run tape length wise at least 1/3 of the inside of belt. You must have a clean edge and 100% adhesion. Itís difficult to find tape wide enough. This was an old stock. I used 2.5 inch tape, although Iím not sure if they make it that wide now. This was 18 inch belt sander and one belt lasted 5-6 hours. The other lasted one-two hours or as soon as you push it hard and it gets hot. In your case if those belts are expensive it might work if you use them for light work but chances are it will just waste time. If they are brand name belts do like what was mentioned and ask the manufacture. All they can say is no. I have been surprised at how good some are.

From contributor W:
Good points and unless I had a semi-quick usage for buying belts in bulk I would not. Humidity kills seams. Were they a common size, seamed overseas and shipped in a container? How long have they been seamed? Glue crystallizes after a certain amount of time and exposure. Abrasive belt converters buy in bulk rolls and seam per order (wide belts, stroke sanding belts) unless it is a fast moving product (3x21, 3x24, 4x24 portable belts).

If we made a belt today, as a previous person stated you would not be able to use it as the glue needs 24 hours curing time (we prefer 36). So, beware the great deal on a bulk amount of belts. It could have been seamed for a long time and ready to pop!