Hi, All -
From a previous post, I noted that I was having problems with Thumler's Tumbler Model B Hi-speed belts breaking all too frequently. The replacement belts are $5-$6 a pop, so this was getting expensive. I went on the search for the equivalent o-ring size in hopes of getting both a cheaper and longer lasting belt.
I measured a new replacement belt and researched the matter. It appears the standard sized o-ring that corresponds with the Thumler's belt size is o-ring number .343 with the following dimensions:
O-ring Size: 3 3/4"ID X 4 1/8"OD X 3/16"CS
I ordered several ethylene propylene o-rings in this size. I'm told this composition resists stretching. They were 80 cents apiece. After my first tumble today using these o-rings, I can report they fit perfectly on my tumbler and works no different than the replacement belt.
Time will tell how long this o-ring will last with continous use, but I'm going to find out. I have a hunch it won't be any worse than the actual replacement belts, and hopefully, will be much better.
I hope this info helps. I haven't seen this equivalent size info posted anywhere else.
Bayou52