The belt on a borrowed 1x42 belt sander I've been using is great for taking the sharp edges off some sterling 16 ga. cut-outs I'm making. It is nearly immortal. I tried replacing it with an aluminum oxide belt but it didn't last very long. There is no longer any information printed on the backing of the blue immortal one I've just about worn out. The owner is 87 and can't remember what it is or where he got it. So, hopefully someone on this newsgroup can steer me in the right direction--what is the best durable abrasive for soft metal?