On 3 Sep 2016 22:46:41 GMT, "DoN. Nichols"
wrote:
On 2016-09-03, Larry Jaques wrote:
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
[ ... ]
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.)
[ ... ]
O.K. They seem to be called "Fenner drive" belts.
Fenner Drive makes that belt, Don. They also make a segmented belt
which can be used in place of a standard V-belt.
O.K. I know about those, but have never used one. (My lathe
runs three parallel belts from the layshaft to the spindle, and I put in
matched belts (ordered from Clausing) to minimize vibration. Not sure
how equal you could make three of those link belts. From what I have
read, they are a bit of a pain to install in crowded places like my
headstock.
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. :-(
Hmm, it shows up at $70.39 when I pull up MSC.
Interesting. It still shows up as $97.62 for me.
Are you perhaps logging into the site instead of just opening
a browser on it? If so, you may be seeing discounts. I know that
recently, after looking up a number of things in the website, when I
place an order, I get significantly lower prices on many items. I just
look through the site as someone not logged in, so I guess that I get
the default price for someone who does not have an account there. :-)
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.
Sounds like a plan!
Someone else posted later in the thread that something around
5-7% stretch is normal tension.
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. :-)
At what speed does dem li'l vibrators run, anyway? I've never had one
apart. Do they use a wildly imbalanced shaft, like a lady's vibrator
or a phone?
I think so. Mount the thing on springs, put an eccentric weight
on a shaft, and spin it. Given the belt drive here, it sounds like the
tension needs to take the shifting on the spring mounts into account, so
perhaps set it up so with maximum spring offset towards the motor, there
is still sufficient tension to keep it from slipping.
I've seen some designs posted where the motor itself is mounted
on the bottom of the bowl, so no belt there. But that probably means
greater eccentric weight needed to vibrate the motor too.
Enjoy,
DoN.
Ayup..Ive several of the units with the motor mounted directly to the
bottom of the bowl..and the weights are pretty good sized. Welded
directly to the bottom of the motor shaft. One of them I know has
bronze bearings..that are worn out..and with the weight welded to the
shaft..no way to take the motor apart to replace the bearings. Due to
the design of the unit..not going to be able to cut the counterweight
off the shaft ...because the motor went in..then..then the welded the
weight after the thing was completly assembled..the bassards.
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