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Post by captbob on Aug 29, 2017 8:31:12 GMT -5
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Post by Drummond Island Rocks on Aug 29, 2017 8:42:53 GMT -5
Neat design. I was trying to figuring out the pulley setup. Goes from small on motor to large on shaft then goes small on shaft to big on barrel. Not sure why it would not just go straight from small on motor to big on tumbler and avoid the shaft and two pulleys. Maybe too early to think so hard here. Would like to see a video of it. Seems the wooden barrel would have more likely of been used for tumbling shell casings. Chuck
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Post by captbob on Aug 29, 2017 8:43:38 GMT -5
Looking at this thing, I'm thinking it was built for some other purpose than tumbling rocks. Like mixing something maybe? Any one have a clue what it was really made for?
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,685
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Post by Fossilman on Aug 29, 2017 9:56:44 GMT -5
Seen on in a museum in Montana,said it was for tumbling shell casings....
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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 29, 2017 22:25:32 GMT -5
Quite a machine, I like those ancient gimbal pillow blocks, noticed one in the picture gallery is missing its bearing[bushing], that will be fun to find. Chuck, the jack shaft between motor and barrel is to provide a double reduction in speed from motor to barrel. Barrel rotates about half as fast as if belt ran directly from motor to barrel. I'd guess each reduction to be ~5:1, so 25:1 overall which means the barrel is still turning around 70 R.P.M., fast for that arrangement.
I agree, likely for something run dry, not rocks.
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Enigman
starting to spend too much on rocks
Member since December 2013
Posts: 163
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Post by Enigman on Sept 17, 2017 17:09:16 GMT -5
Neat design. I was trying to figuring out the pulley setup. Goes from small on motor to large on shaft then goes small on shaft to big on barrel. Not sure why it would not just go straight from small on motor to big on tumbler and avoid the shaft and two pulleys. Chuck It's called a compound reduction system. The first shaft reduces the motor speed by the ratio of the motor to first shaft pulley circumferences. Then the small first shaft pulley connected to the large barrel pulley reduces the speed again by the ratio of the small pulley to the barrel pulley circumferences. It's a multiplicative reduction. For example, if the motor pulley circumference was 3 and the first shaft large pulley was 30, then the motor speed is reduced by 10 to 1. Likewise if the first shaft small pulley circumference was 3 and the barrel pulley was 30, then the motor speed is again reduced by another factor of 10 to 1 for a overall total reduction of 100 to 1. This is how the low gears in an auto transmission work. By compounding the ratios you save a lot of size. If the machine did not use that intermediate pulley shaft, then the barrel would have to have a pulley with a circumference 100 times larger than the motor pulley in order to get the same overall RPM reduction. That would have made the barrel pulley about as big as the barrel.
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Post by coloradocliff on Sept 17, 2017 17:17:25 GMT -5
Looks for sure like Rube Goldberg machine. Pulley set up seems without rhyme nor reason. Maybe a small difference in size of one to adjust the speed that we aren't seeing.
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Post by Pat on Sept 17, 2017 17:46:38 GMT -5
Interesting! Reminds me of a mouse trap. I think some parts are missing.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Sept 17, 2017 18:04:08 GMT -5
Yep, I was thinking shell casings too. That kind of tumbler goes way back while rock tumbling is pretty recent I'd guess. Much lower abrasion than tumbling rocks. I would think rock tumbling grit would cut right through a wooden barrel. Still cool beans on that neato gizmo....Mel
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