lapidarius
off to a rocking start
Member since August 2016
Posts: 4
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Post by lapidarius on Aug 12, 2016 21:49:48 GMT -5
I just got a Thumler Model B and so far so good. Aside from the barrel walking to one side and grinding on the idler shaft guide, which seems fairly common and minor, no issues.
The body has other slots for the idler shaft, and it seems like an easy way to speed the tumbling up. Does anyone have more detailed observations or tips about using these? With the idler shaft in the third slot, the barrel speed is 22RPM.
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huskeric
spending too much on rocks
Member since May 2016
Posts: 353
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Post by huskeric on Aug 14, 2016 18:12:28 GMT -5
I can't say for certain, but I *believe* the other slots are for the 3lb barrels. That frame looks quite a bit like it could be set up to run 4 3-pounders. I would be a little nervous about moving those shafts in and running that giant barrel, just from a stability standpoint. I did see that they make both a low-speed and a high-speed motor for that guy, but not sure you want to go to that expense. I am far from an expert, but depending on what you're tumbling, in a barrel that large, you may not want to go much faster than that so that you don't bruise your rocks.
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salpal48
starting to spend too much on rocks
Member since March 2015
Posts: 136
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Post by salpal48 on Aug 14, 2016 18:53:00 GMT -5
I have used the other slots to speed up the nachine but they are designed for the Other drums that Thumler makes Sal
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lapidarius
off to a rocking start
Member since August 2016
Posts: 4
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Post by lapidarius on Aug 18, 2016 20:41:24 GMT -5
I timed the barrel with the idle shaft in both the 4th and 3rd slots. 4th slot: 21.5 RPM, 3rd slot: 22 RPM. Using the third slot also caused the drive shaft to pull on the belt, so it’s running on the 4th slot.
My understanding of what makes the barrel spin at a certain speed isn’t complete, obviously.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Aug 19, 2016 0:02:27 GMT -5
Changing the location of the idler shaft won't make any change in the barrel speed. This is accomplished by changing drive or driven pulley sizes relative to each other, smaller drive relative to driven slows the barrel, smaller driven pulley relative to drive pulley speeds up the barrel. Changing the size of the rollers on the drive shaft act in the same manner.
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