On 3 Sep 2016 04:21:12 GMT, "DoN. Nichols"
wrote:

On 2016-09-02, Gunner Asch wrote:
I have a vibratory cleaner...that uses a "o-ring" type drive belt to
power the bowl. Which material type O ring will last the longest?

I use it to tumble/polish cartridge cases. Originally it came with a
"universal" belt..basically a tube and a splice barrel that one cut to
size, and used the splice piece to join the ends into a circular belt.
I ran out of the belt material a few years ago and havent found any
since then. Ive been cleaning up a bunch of cartridge brass...about
100 lbs so far, using some O-rings I had kicking around..but I had to
stretch them pretty far to get them to fit between the
pulleys...which gave them a very short life span. Since Im going to
have to order a bunch of O rings, which material should I be looking
for? The pulleys are in good shape and are of proper half round
grooves...for about a 3/16" round belt.

Look into your MSC catalog. There is a urethane rubber round
belt material (I've got two sizes, translucent orange and opaque green),
which you buy in rolls. I got them to make belts for a Unimat and a
Jeweler's lathe.) Cut it to the desired length, get a piece of material
with a thickness about the diameter of the material, machine a V-groove
in the edge and clamp in a vise to hold it steady. Hold both ends of
the belt in a flame from a propane torch or the like, then squeeze the
ends together, using the V-groove to keep them alligined, let them cool,
and use a razor blade to trim off the flash which will ooze out.

O.K. They seem to be callled "Fenner drive" belts.

For your 3/16" diameter, try MSC catalog number "35364579".
They are asking $97.62 for a roll of 100 feet. Seems to have gone up
since I got mine. :-(

Secondly...how much tension would be best for this application? How
much stretch should I allow for, when ordering them? Obviously too
much elongation is bad for the belt...what would be appropriate?

With the above materials, you can make them to your needs, so
you don't have to worry about too much stretch. Obviously, the tension
is a function of the load and the speed. Start out by making it just a
very slight stretch and see if it will handle the load without slipping.
If not, trim out the part where you spliced it and try again --
shortening it perhaps 5% or so.

With too much speed, they will add their own tension, stretching
towards a full circle. But for cartridge tumbling speeds, I don't think
that you have to worry about that. :-)

Enjoy,
DoN.

Many thanks Don!!

Gunner

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