Gerry
It shouldn't be rocket science to join cloth sanding belts. Back in the '70s I worked at a company that manufactured wood office furniture. Many times I watched John the assembly shop foreman make sanding belts for the horizontal belt sander that were over 10 feet between pulleys. They bought the sanding belts in several different grits in bulk rolls probably several hundred feet long.
He would lay one end of the belt over the other in such a way that when he cut them at an angle one would be the exact opposite of the other and produce a perfect match. He then had a grinder set up that would cut the grit off the belt for about an inch on both ends. Now he laid one side of both ends of the belt against a straight edge and allowed them to overlap about 7/8". He then put a thin coat of glue on both surfaces and made sure it was rubbed in good with minimum excess. He now laid a short piece of wood on top of the joint an put a couple of small nails through to hold it in place.
He would leave it sit there till the next day then make another. The glue that he used was the same glue that they used to glue all the wood parts together. So any good grade of wood glue should work OK.
Hope that this is some help to you. If you are using these belts on metal and there is any oil involved you may have to clean the joints with alcohol if re-gluing a joint.
Cheers
Don
PS: Type this into google and search. "
How do I make a sanding belt?" It will give you more info than you want to read.
Don
