Hi i have a galaxy 506 i just buy brand new i had a clark american 8 " before but now i'm having problem with the sanding papers when i instal the sanding paper on the drum some times it broke inside when i tight it up and some time when i start the sanding it broke ...? i think it has something to do with the shim exemple grid 40 i shim with 2 x 100 grid ? well enyways my question is if i use grid 36 -40-60-80-100 what are the good shims or what could cause this issue ? need help please from a sander guy ; )

I dont think there is one shim scedule that works across the board. Its more likely just going to be trial and error kind of thing. Getting the paper too tight will blow it every time. As the drum heats up it expands causing the paper to tighten up. So you have to give the paper just the perfect amount of slack (usually just a 1/4 turn back on the cam) for it to run right. The galaxy probally has a diffrent type of rubber than the clark and spins at a diffrent speed as well as a motor thats quite a bit bigger as well. I would call Galaxy and talk to a tech person they might be able to shed a little more light.