FRODO, Posted May 24, 2013 Share Posted May 24, 2013 ] i have made a brass tumbler for my reloading hobby. i need to reduce the rpms to around 50 ... do i increase the drive pulley size? the belt is 36" long the pipe a 6" pvc Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted May 24, 2013 Share Posted May 24, 2013 Increasing the drive pulley diameter will INCREASE the speed! Your current drive pulley is as small as you can go... you'll have to add another drive belt and double pulley to gear it down. Alternatively you could use a slower motor. Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 24, 2013 Author Share Posted May 24, 2013 .ok, sounds simple enough. is this what your are talking about? what size pulley do you think i need to add? its 12 1/2" center to center now Quote Link to comment Share on other sites More sharing options...
John B Posted May 24, 2013 Share Posted May 24, 2013 That configuration is not going to alter the rpm one iota, Bigfoot was suggesting what I believe in the styates is called a jackshaft arrangement. Rpm's can be calculated, but your motor rpm must be known and then pulley sizes and arrangements can be worked out. Quote Link to comment Share on other sites More sharing options...
ironsmith Posted May 24, 2013 Share Posted May 24, 2013 below is a jack shaft set up for a go kart., at #2 and #3 is the other shaft. you can use pillow block bearings to mount the shaft and a pulley on each end. #1 would be your motor and #4 would be the final driven part of your setup. Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 24, 2013 Author Share Posted May 24, 2013 ohhhhhhhhh. light just came on... i got it... an extra shaft with 2 pulleys is needed to transition the rpms i have the jack shaft figured out. . yeah i was way off. thanks for splaining it to me drive shaft turns 7 times to the final drives 1 final drive is 6 1/2" i looked on line and found a rpm number for whirlpool # 279827 is 3450 rpm can that be throttled down? Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted May 24, 2013 Share Posted May 24, 2013 Smaller drive pully = slower belt speed Bigger driven pully = slower drum rotation. The drive pully turns at motor rpm, but the bigger the circumpherance the faster the belt travels. The driven pully rpm is dependent on the outside circumpherance of the pully, the bigger the pully the farther the belt has to travel to turn the shaft 1 rpm. Using a jack shaft alows you to use smaller pullies. I remember how to do the math bu I'd have to look up the formula or reinvent the math. The diferance in the circumpherius of the puppy's is the ratio that the driven saft will be driven. I know farm equipment and such has say 2' pullies. Coupled with say a 1 1/2" drive. I think 2 Pi R is the formula you need Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 24, 2013 Author Share Posted May 24, 2013 i gotta study that. pi x radius is above my pay grade!! i might not have enough toes. :rolleyes: Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 24, 2013 Author Share Posted May 24, 2013 tried to edit my post, could not find the button :wub: I was wrong its 1750 rpm not 3400 I marked the shaft, and marked the drum turned them and counted 7 revolution to 1 barrel revolution Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted May 24, 2013 Share Posted May 24, 2013 Ok, so that's 250 RPM at the drum. So we need to slow the drum down by a factor of 5, either find a dive pully 5x smaller around the out side, or. A driven one 5x bigger around the outside, or split the diferance. The drive pully is probably prety small already. So go looking for a big drive pully or build a jack shaft to reduce the speed by 1/5. Quote Link to comment Share on other sites More sharing options...
Dave51B Posted May 25, 2013 Share Posted May 25, 2013 Or,,,,you could drive the rollers and let the pipe just ride on them.......Dave Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 25, 2013 Author Share Posted May 25, 2013 be cheaper to jack shaft it. altho i like your idea of driving the pulleys. that could be done with a tread mill. :D if i jack shaft do i use a 5" and a 2" pully ? big pulley on the drive side little on the drum ? Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted May 25, 2013 Share Posted May 25, 2013 For a jack shaft, use a big pully on the side coming dom the motor, and a small one on the side going to the drum. If you want to get snazy put a 3 in one cone pully on the driven side. Then hange the motor so it's weight tensions the belt. That way you will have a three speed tumbler. Quote Link to comment Share on other sites More sharing options...
FRODO, Posted May 25, 2013 Author Share Posted May 25, 2013 i sharpened my pencil and had to take off my shoes, but i figured it to be. a 4 1/2" pulley and a 2" pulley will get me to 60 rpms around 2 am i put 250 308 brass cases in the tumbler. it spun the brass up to the side and they stayed there yep...gotta turn it down Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted May 29, 2013 Share Posted May 29, 2013 I think 2 Pi R is the formula you need I never understood what the difference was between 2 Pi R and Pi D I always just think in terms of 3.142 times the diameter. You can get there roughly with "three times and a bit" if you are doing it in your head! big pulley on the drive side little on the drum ? If you are familiar with derailleur gears on a bicycle it may help with the principle. The big sprocket on the (driven) back wheel is for going up hill (slower) the little one for down (faster)! [....i put 250 308 brass cases in the tumbler. it spun the brass up to the side and they stayed there yep...gotta turn it down....] I made a little tumbler for my jewellery work from an old 33rpm record deck tilted at 30º with a plastic face cream tub held on by a 3 prong copper claw. I played with the tilt until it just tumbled. You might try your tumbler with fewer cases to see if it will tumble them at that speed...try 25 and increase until the load is too high. Are you tumbling wet or dry? Using soap and brass clippings or a proprietary abrasive? Used (!) primer caps or .22LR brass could be good.... Alan Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted May 29, 2013 Share Posted May 29, 2013 There isn't a diferance, but for some reason the math types chose to express it that way. Besides that's how I remember it, and after raising two daughters being able to remember anything is a miricle! If the math hurts your head, no problem as my old shop teacher was fond of story boards, use a piece of string around the outside to gage the pully, double the distance around reduces the RPM of the driven by 1/2 As to a jack shaft being less expensive than a larger pully. Maybe, maybe not. You have to by two pullys, and two pilowblocks and the shaft. Unles you scrounge them up. That said, two big evap cooler pulys as driven pullys, and two evap driven pulys with a jack shaft should get you a significant degree of slow. If you use somthing like a salvaged treadmill motor, they are stepper motors and use a controler. Just dial it in to the speed you want. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted May 29, 2013 Share Posted May 29, 2013 There isn't a diferance, but for some reason the math types chose to express it that way. Strange and wonderful people those math types! I too was taught it that way but prefer Pi D for quite pragmatic reasons. One advantage I find of the keep-it-simple version Pi D is that you don't get muddled between it and Pi R2 In this instance being able to see that it is a simple ratio between diameter and circumference means that you can just say... if a pulley is twice the diameter it is twice the circumference and therefore will rotate at half the speed. Four times the diameter = quarter the speed, five times the diameter = 5th of the speed.... Alan, a Pooh of little brain! Quote Link to comment Share on other sites More sharing options...
ianinsa Posted May 30, 2013 Share Posted May 30, 2013 Alan, a Pooh of little brain! "Pooh" the bear?...... He wot made famous--T.T.F.N.? and for those that missed out in their youth it stands for TA,TA FOR NOW! as in good bye. Quite a smart bear as I recall, Lots of freinds but not as natty a dresser as Rupert. ;) Ian Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted May 30, 2013 Share Posted May 30, 2013 That's the one. Dresses were never really my thing! :) Alan Quote Link to comment Share on other sites More sharing options...
swedefiddle Posted May 31, 2013 Share Posted May 31, 2013 Pi R2 = surface area Pi D = Circumference Cake R Square Pie R Round :) :) Neil Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted June 1, 2013 Share Posted June 1, 2013 Pi R2 = surface area Pi D = Circumference Cake R Square Pie R Round :) :) Neil Now now, don't turn this into a bun fight! Crumbs! that was a stale pun... Alan Quote Link to comment Share on other sites More sharing options...
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