I ran into a similar situation at work when repairing one of our scientific
instruments that has a motor driven spindle. The manufacturer was happy to
quote me a replacement drive belt for $20!
I found a standard o-ring that matched the size, and it appeared to be
identical in every way to the original. Total cost was about 10 cents!
Standard industrial O-rings come in 5 different cross-section diameters. For
each cross section, there are a range of sizes listed by inside diameter.
Each specific size is identified with a 3 digit "dash number" (-XXX), where
the first number identifies the series (and thus x-section dia), and the
last 2 numbers determine the ID.
-0XX .070 in
-1XX .103 in
-2XX .139 in
-3XX .210 in
-4XX .275 in
For your application, the -0XX series has the closest matching cross
sectional diameter. Next, you have to look up the ID's available in that
series from a chart. One place to see a chart is www.mcmaster.com. Navigate
to their catalog page #3271.
Back calculating the ID based on your OD measurement (subtract twice the
cross section), I get a nominal ID around 1.36 in. On the McMaster-Carr
online catalog page #3271, find:
The nearest match is: a # -028, with actual ID = 1.364", and actual OD =
The general purpose, black rubber composition, "BUNA-N/nitrile" type will
work just fine.
Since you probably don't want to buy their minimum qty of 100, ask for a
#-028 from your local hardware store or machine shop.
<<Well, while powering up today for the weekend contest one of my Yaesu
control box indicators failed to turn. So I pulled out one of the spare
boxes and plugged that in... unfortunately when I turned it on the indicator
motor spun up to full speed but the needle didn't move! Opening it up
showed a broke drive belt... looks like dry rot of the rubber as there are
some other small cracks in the rubber. Besides looking like a real pain to
replace, does anyone know of a source for these little rubber belts? And
how to specify them?? It looks to me more like an o-ring than something
meant for driving a gear train. But anyway, its about 1.5" in diameter, or
about 4.75 in circumference and 1/16" thick.
David Robbins K1TTT >>
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