stonemaster499
noticing nice landscape pebbles
Member since July 2014
Posts: 97 
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Post by stonemaster499 on May 12, 2015 22:05:06 GMT -5
My Thumler's model B's spin 22 RPM empty, and 18-20 RPM full. While this speed works for all round general use, it is not ideal for Hard Stones [H.7 - (chalcedonies: agates and jaspers)] I want my hard stones to spin at 32 RPM, in order to get the same results in 1/3 time. I would also advise using GREEN 46 grit SiC or G46SiC. The lower grit size, and the increased speed should cut your grind time by at least 40%, and decrease your abrasive use, since you will have less grinding cycles. If you really want to speed things up, go hard-core, and get Green 17 grit SiC or G17SiC (50% decrease in standard tumbling times). I would also like to "introduce" to the tumbling world (RTH) Green Silicon Carbide. Green is a higher quality Silicon carbide, more pure crystals which are harder and more aggressive. You can get by perfectly fine with using black silicon carbide, but it will be less efficient. In General the green is ***15-30% more efficient, and ***15-30% more expensive. ***I only recommend GSiC for harder stones, and would consider quartz fine with black SiC. Since time is money, anyway I can speed up the process counts. Thumler's model B mod: The simplest way to speed up the process is to mod the drive shaft by adding diameter. I first used black electrical tape. It worked well, but wears out over time, and needs to be adjusted every few months to keep the speed. Then, I thought of hockey stick tape. Brilliant...Until i put it on... nightmare. It gets so gooey, wow, I don't even know how I recovered by somehow removing it. Finally, I switched to non-adhesive, self fusing rubber tape and all is well. 1" x 6'-8" perfect for one application, and mine as not needed to adjusted in the last 3 months, but did drop to 30 RPM recently, so perhaps the tape has leveled a bit, and requires a slight addition to get back to 32 RPM/ I used 34" of tape wrapped around each roller of the Drive Shaft. Drive Shaft Mod (see video) I was prepared to add, more, but my speed ended up at my desired 32 RPM. Sometime it takes a few minutes to get up to speed! Since you are adding more force to the motor, you might need to help it start, and or run the tumbler first and then place the barrel. The motor will run a bit hotter, and you might decrease its life proportionally with the increased use. Mine has been Modified since Aug 2014, and runs pretty much 24/7 without an issue. Yes you can get the same results by increasing the pulley as well, but don't have the speed control by adding or subtracting tape. I have an extra drive shaft, so if I need to switch back to standard speed, I only need to switch out the drive shaft, and have a 2 speed rotary tumbler. This gives me much more control of my product, and much more use and pleasure of the machine. **If you have the High-speed model B, you already have the perfect machine for harder stones. To slow down your tumbler for quartz and softer: Get an extra drive belt, and decrease diameter of the foam rollers (for example sand them down), or ideally replace the pulley with a smaller one. If your tumbler wonders to either side, which is a general problem with this design (especially if not running flat), you can add a washer below the bottom of the side it is wandering towards to correct. Thanks to Connrock for that idea, and you can see this in the video as well with my standard model B (left side, Barrel #1 was wandering to the left, so I added a washer below the right side to correct. Enjoy! |
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quartz
Cave Dweller 
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,359
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Post by quartz on May 12, 2015 22:37:52 GMT -5
What diameter did you end up with on the tape-up, would a piece of airline or fuel line hose have ended at ~the same dia., and not had as much of a maintenance requirement? Just a thought. I've used the hose on a couple small tumbler builds and it lasts very well.
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Post by captbob on May 12, 2015 23:08:57 GMT -5
Why does your motor run hotter? It's still turning the same RPM.
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jamesp
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Member since October 2012
Posts: 36,602
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Post by jamesp on May 12, 2015 23:35:30 GMT -5
Motor is same RPM but moving rocks at a faster rotation. Like driving up a hill in 3rd gear instead of 2nd gear at 3000 RPM in each case.
Car moving faster at 3000 in 3rd gear, burning more fuel than 3000 in 2nd gear, a slower speed.
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stonemaster499
noticing nice landscape pebbles
Member since July 2014
Posts: 97
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Post by stonemaster499 on May 12, 2015 23:52:46 GMT -5
quartz. Good idea. I like the play with the tape. I think I doubled the diameter (see the video), but since it is not perfect it does even out over time, or settle. Once settled it seems to be stable. Attaching a larger pulley is the real way to go, but I don't have the patience or energy to do so.
In the beginning, i had to keep adding and checking until I reached the desired speed.
jamesp - exactly.
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Post by captbob on May 13, 2015 0:16:33 GMT -5
I'm going to need another example. Yours may make sense, but I'm not following that. Motor pulley is still turning 1500 RPM. Drive shaft pulley still turning whatever it was regardless of the added tape. The extra thickness of the tape is what is causing the barrel to rotate faster. Why should this effect the motor when It's still doing what it was designed to do? Your example puts more strain on the motor due to the transmission, because the transmission is acting like a governor and causing the motor to work harder thus run hotter. No transmission here, so I'm not getting why the tumbler motor would care about the tape. Gonna have to put my puzzler to work...  |
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jamesp
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Member since October 2012
Posts: 36,602
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Post by jamesp on May 13, 2015 6:40:12 GMT -5
If you halved the shaft size you would halve the barrel speed.
If you doubled the shaft size you would double the barrel rotation speed.
If you quadrupled the shaft size you would quadruple the barrel rotation speed.
Taking it to extreme, if shaft was same diameter as barrel, the shaft and the barrel would be turning at the exact same speed, very fast.
Basically the shaft and the barrel are two gears or pulleys since they do not slip.
Of course, anything you do to the pulleys or shaft that increases the speed of the barrel makes the motor work harder.
Stonemaster is correct, factory tumblers are set up on the slow side for soft and hard rocks alike.
Agate can and should be turned a lot faster. I rough Rio agates and coral at 55 RPM. 220-500-1000 and polish at 30 RPM.
55 RPM(*using 7.5 inch barrel) requires kinda heavy duty almost industrial system. And a well balanced load of rocks and barrel filled to 3/4.
I think the factory would never want the product liability of a 55 RPM tumbler. Fingers and shirt tails may get caught up in it.
It would raise the cost of their required product liability insurance. (regulatory limitations at work protecting our dear citizens)
More expensive components. Barrel failures/wear, increased gas generation, too much noise, etc.
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Post by captbob on May 13, 2015 9:01:32 GMT -5
Of course, anything you do to the pulleys or shaft that increases the speed of the barrel makes the motor work harder. WHY? Is the tape putting a strain or extra load on the motor? How so? Sorry, but this isn't making a lick of sense to me. I can understand that if you were to grab each end of the drive rod and squeeze that the motor would have to strain because you are putting a brake (governor) on the shaft. Actually the drive belt may slip in that case, but let's say it didn't. Anyway, by physically hindering the natural rotation of the drive rod you are causing the motor to labor under an abnormal load. The motor isn't going to speed up to handle the additional load. There is no driver pushing the gas pedal further. Motor is same RPM but moving rocks at a faster rotation. Like driving up a hill in 3rd gear instead of 2nd gear at 3000 RPM in each case. Car moving faster at 3000 in 3rd gear, burning more fuel than 3000 in 2nd gear, a slower speed. In this example, something or someone had to apply extra "juice" to keep the motor running at 3000 RPM. It sure didn't maintain a constant RPM on it's own when a drag/load/governor was applied. If you add more weight to the barrel, the motor may labor from the additional load, and probably slow down because there is no additional power out put (gas pedal) option. I got that a motor will run hotter, or slower, when subjected to an increased load. Something about drag and stuff like that I reckon. Understood. Clear as a bell. What I don't get is how the tape on the drive rod constitutes an increased load. How does it impede the natural running of the motor? The tape is acting as an addition gear/pulley to speed rotation. That's what gears & pulleys have been about since their invention. Getting more work from the same output. The tape (an extra gear/pulley) means faster rotation from the same RPM. Where is the added load? Pretty sure there is something requiring less thinking that I should be doing... |
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matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
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Post by matt2432 on May 13, 2015 9:44:43 GMT -5
The added load is due to the torque. Torque is force X distance. For example, is it harder to close a door from the handle or by pushing a foot out from the hinge? The same door is being moved, but it takes more work to move it because you have less torque. Same thing with the tumbler, the same load is being rotated, but it requires more work to rotate it because there is more or a reactionary force acting against the rotation of the motor. More torque due to the increase diameter of the drive shaft.
Like Jamesp said, it all proportionate to the diameter. The farther out from the center of rotation you are, the more torque there is.
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Post by johnjsgems on May 13, 2015 9:52:12 GMT -5
Anytime you increase the driven pulley size you increase the speed thus increase load and amount of work motor does. Pulley replacement would be better than tape. I don't think they make adjustable sheaves with that small of bore but that would be even better.
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Post by captbob on May 13, 2015 10:01:55 GMT -5
Anytime you increase the driven pulley size you increase the speed thus increase load and amount of work motor does. Wouldn't increasing the size of the pulley on the drive rod slow rotation? My head hurts... |
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Post by cobbledstones on May 13, 2015 10:20:32 GMT -5
captbob, surface feet per sec of the shaft (and the tumbler barrel) increases as the shaft gets thicker, assuming motor RPMs and pulleys remain the same. then power (in Watts) is force*speed where the force is related to the weight that the motor has to lift (rocks in barrel) to make the whole thing turn. Of course friction and efficiencies have to be taken into account as well. So, thickening the shafts--> greater surface speed --> greater required power -->hotter motor
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Post by johnjsgems on May 13, 2015 10:21:38 GMT -5
You are correct, I got it backwards. I thought he was taping the pulley rather than drive shafts. A smaller driven pulley or larger motor pulley would increase speed. Same concept though. increasing the shaft size would change barrel speed since every turn of the larger shaft would move barrel farther so more load on motor. Braided hose over the shafts would likely last longer than tape. I use "Tygon" tubing on the used tumblers refurb. The garden hose with webbing works well too but Tygon is sold by the foot at most hardware stores.
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Post by captbob on May 13, 2015 11:13:41 GMT -5
Still feeling kinda stupid for not grasping this. Let me ask this way... If you were to put a smaller diameter pulley on the drive shaft, which would make the barrel rotate faster, would that make the motor work harder or run hotter? If so, why? The motor is still doing the same thing it was doing with the original, bigger pulley. Just not seeing how -without physically impeding the rotation of the drive shaft or adding to the load - that changing the pulley (or using the tape on the rollers) would effect the performance of the motor. The tape is not changing the size of the pulley rotating the drive shaft. YES, that would change rotation speed, which is what you are trying to do, but that's what pulleys are for - altering output with no change in the force needed. I'm of a mind that, resistance and load aside or at least being equal, the job of the motor ends at the pulley that it is tasked to turn. What happens beyond the pulley (rotation speed in this case) is the job of the pulley and parts beyond. If I were to use a thinner drive shaft or rollers on the shaft, thus causing a slower rotation, would the motor work any less hard or run cooler? I don't think so, (resistance and load being equal) because it is still turning the same pulley and load. Say you have a hamster. And you have 2 wire wheels that they like to run in. An 8" wheel and a 12" wheel, The wheels weigh the same and have the same resistance factors. The hamster running in the 8" wheel will create more RPM than when running in the 12" wheel - all while running at the same speed. The hamster doesn't care. It's not going to get hotter from running in the different wheels. Why should a motor?  probably should have taken that physics class instead of underwater basket weaving... |
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stonemaster499
noticing nice landscape pebbles
Member since July 2014
Posts: 97
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Post by stonemaster499 on May 13, 2015 12:05:57 GMT -5
Still feeling kinda stupid for not grasping this. Let me ask this way... If you were to put a smaller diameter pulley on the drive shaft, which would make the barrel rotate faster, would that make the motor work harder or run hotter? If so, why? The motor is still doing the same thing it was doing with the original, bigger pulley. Just not seeing how -without physically impeding the rotation of the drive shaft or adding to the load - that changing the pulley (or using the tape on the rollers) would effect the performance of the motor. The tape is not changing the size of the pulley rotating the drive shaft. YES, that would change rotation speed, which is what you are trying to do, but that's what pulleys are for - altering output with no change in the force needed. I'm of a mind that, resistance and load aside or at least being equal, the job of the motor ends at the pulley that it is tasked to turn. What happens beyond the pulley (rotation speed in this case) is the job of the pulley and parts beyond. If I were to use a thinner drive shaft or rollers on the shaft, thus causing a slower rotation, would the motor work any less hard or run cooler? I don't think so, (resistance and load being equal) because it is still turning the same pulley and load. Say you have a hamster. And you have 2 wire wheels that they like to run in. An 8" wheel and a 12" wheel, The wheels weigh the same and have the same resistance factors. The hamster running in the 8" wheel will create more RPM than when running in the 12" wheel - all while running at the same speed. The hamster doesn't care. It's not going to get hotter from running in the different wheels. Why should a motor? probably should have taken that physics class instead of underwater basket weaving...When you increase the pulley, or increase the diameter of the rollers, you increase the speed. The motor and shaft speed don't change! The pulley was set for 20 RPM. If the manufacturer wanted the barrel at 10 RPM the pulley would be more or less 1/2 the size. Drive shaft and motor DO NOT change. Motor would have LESS load/force/heat. The opposite occurs when you increase the diameter of pulley or rollers on drive shaft. LARGER PULLEY/DRIVE ROLLERS = MORE SPEED = MORE FORCE = MORE HEAT (at motor and in barrel) = MORE TUMBLING INSANITY  |
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Post by johnjsgems on May 13, 2015 12:12:54 GMT -5
If the outside of the shaft is larger, the barrel will turn farther each turn of the pulley. Any movement of the barrel is the load on the motor. Turning it farther is an increase in load. The hamster in the larger wheel runs farther each turn of the wheel than the critter in the smaller wheel. It is opposite with pulleys. A 2" motor pulley making a complete revolution will turn a 4" pulley one half revolution. Just picture circumference and it makes sense.
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Post by captbob on May 13, 2015 12:20:53 GMT -5
When you increase the pulley, or increase the diameter of the rollers, you increase the speed. The motor and shaft speed don't change! The pulley was set for 20 RPM. If the manufacturer wanted the barrel at 10 RPM the pulley would be more or less 1/2 the size. Drive shaft and motor DO NOT change. Motor would have LESS load/force/heat. The opposite occurs when you increase the diameter of pulley or rollers on drive shaft. LARGER PULLEY/DRIVE ROLLERS = MORE SPEED = MORE FORCE = MORE HEAT (at motor and in barrel) = MORE TUMBLING INSANITY You are saying that if the black pulley on the drive shaft were larger in diameter that the barrel would rotate faster? I give up... totally lost... good thing I never tried to build a tumbler! |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,602
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Post by jamesp on May 13, 2015 14:47:30 GMT -5
You can do calculations with RPM that may help.
1 inch pulley on motor and 3 inch pulley on roller shaft is 1/3 cut in motor speed of roller shaft. 1/3 X 1500 RPM = 500 RPM at roller shaft.
If you switch pulleys and put 3 inch pulley on motor an 1 inch pulley on roller shaft you will speed the roller shaft 3 times. 3 X 1500 RPM = 4500 RPM at roller shaft !!!!!
1 inch pulley on motor and 4 inch pulley on roller shaft is 1/4 cut in motor speed of roller shaft. 1/4 X 1500 RPM = 375 RPM at roller shaft.
If the roller shaft is tuning 500 RPM and barrel is 8 inches and roller shaft is 1 inch your barrel will turn 1/8 X 500 RPM = 62.5 RPM.
If roller shaft is turning 500 RPM and barrel is 12 inches and roller shaft is 2 inches your barrel will turn 2/12 X 500 RPM = 83.33 RPM.
So there is a sped relationship between the roller shaft size and the barrel size.
At least the final RPMs are noted so it may be clear, nonetheless, it is a strange but perfect ratio situation. It is all about ratios.
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Post by johnjsgems on May 13, 2015 16:50:01 GMT -5
It would seem like bigger would be faster but as I explained bigger turns less distance per revolution of drive pulley. Less math, just common sense.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,722
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Post by Fossilman on May 13, 2015 18:20:17 GMT -5
LOL,I'm going to stick to my small Lortone tumblers-I'm not in a hurry anymore in life....I got a headache from just the read!
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