leisa
off to a rocking start
Member since January 2015
Posts: 17
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Post by leisa on Dec 13, 2021 6:02:28 GMT -5
My brother built this for me. It is going 48 RPM, but seems fast to me. We only started it yesterday. The barrels mainly have beach rocks from Lake Superior and churt from a quarry in Janesville, WI. They are turning the opposite direction of the Lortone and Thumler tumblers I have. Does that matter? Thanks.
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brybry
Cave Dweller
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Member since October 2021
Posts: 1,220
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Post by brybry on Dec 13, 2021 6:37:22 GMT -5
The direction doesn't matter. You could just flip them around if you want for S&Gs.
I have 3 pounders rolling that fast myself along with a 17 pounder rolling fast. If you need to tone it down, put a larger pulley on it. For anything more delicate/touchy, add extra cushion if you decide to leave it rolling fast.
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isetta
off to a rocking start
Member since December 2021
Posts: 2
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Post by isetta on Dec 13, 2021 7:10:07 GMT -5
HI I am the brother who is trying to make a rock tumbler for my sister. She feels 48rpm is too fast. I am using a two inch pulley on motor end and 6 inch pulley on tumbler end. If you feel my sister is right and 48rpm is too fast then I am assuming I need to increase the pulley size on the tumbler end. It is too hard to decrease the pulley on motor end. The question is should I get a 7inch or a 8inch pulley. I rather get it right then guess. and be wrong. I am trying to keep myself out of the doghouse and I really do not know is 48rpm is too fast or is the 6inch pulley okay. I knew the answer about rotation of motor does not matter but wanted to verify. to sum up should i change size of pulley? Thanks
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Post by rockjunquie on Dec 13, 2021 8:11:30 GMT -5
HI I am the brother who is trying to make a rock tumbler for my sister. She feels 48rpm is too fast. I am using a two inch pulley on motor end and 6 inch pulley on tumbler end. If you feel my sister is right and 48rpm is too fast then I am assuming I need to increase the pulley size on the tumbler end. It is too hard to decrease the pulley on motor end. The question is should I get a 7inch or a 8inch pulley. I rather get it right then guess. and be wrong. I am trying to keep myself out of the doghouse and I really do not know is 48rpm is too fast or is the 6inch pulley okay. I knew the answer about rotation of motor does not matter but wanted to verify. to sum up should i change size of pulley? Thanks Welcome to the board!
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Post by Drummond Island Rocks on Dec 13, 2021 8:46:09 GMT -5
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Post by HankRocks on Dec 13, 2021 9:34:46 GMT -5
Drummond Island Rocks Looking at your tumbles never gets old. The quality of the tumbles always makes me wonder about how formation process, especially the last 3.
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isetta
off to a rocking start
Member since December 2021
Posts: 2
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Post by isetta on Dec 13, 2021 10:57:19 GMT -5
I am using a 2 motor pulley. The pulley on the tumbler end is a 6 inch pulley. the 6 pound drum is spinning a 48rpm. should I increase size of pulley on tumbler end to what size and decrease the pulley on motor end to 1.5 inches and what would be a good speed for the drum to turn at. The motor is 1725 rpm.
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dshanpnw
fully equipped rock polisher
Member since December 2020
Posts: 1,071
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Post by dshanpnw on Dec 13, 2021 12:38:47 GMT -5
Hello Isetta, my 12 pound lortone barrels rotate at 24 RPMs and the 3 pound ones at about 42 RPMs. I built a small tumbler and to get the RPMs of the barrels right I had to change the pulley size once, the first one was too small and had them going too fast. It is best to ask for help first, it does save time and a little money. I think you're very close to getting it just right. Consider all the factors just like Drummond Island Rocks stated.
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Post by Drummond Island Rocks on Dec 13, 2021 13:36:29 GMT -5
I am using a 2 motor pulley. The pulley on the tumbler end is a 6 inch pulley. the 6 pound drum is spinning a 48rpm. should I increase size of pulley on tumbler end to what size and decrease the pulley on motor end to 1.5 inches and what would be a good speed for the drum to turn at. The motor is 1725 rpm. A range of 24-30 is great for 6 and 12 pound barrels. 42-50 is good for 3 pound barrels. You do not need to be exact by any means just shoot for those ranges. Stick a piece of tape on the side of the barrel and count rotations for 30 seconds and multiply by 2. I am using a 1725 motor, 1.5 motor pulley, 1" final diameter shafts and 10" main drive pulley. Your final diameter of your shafts look smaller so that variable is going to change what size main drive pulley is required. What is the O.D. of your shaft covers? Chuck
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Tommy
Administrator
Member since January 2013
Posts: 12,881
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Post by Tommy on Dec 13, 2021 15:05:03 GMT -5
I am using a 2 motor pulley. The pulley on the tumbler end is a 6 inch pulley. the 6 pound drum is spinning a 48rpm. should I increase size of pulley on tumbler end to what size and decrease the pulley on motor end to 1.5 inches and what would be a good speed for the drum to turn at. The motor is 1725 rpm. Isetta, welcome. You're in good hands with the pro tumblers here but just wanted to add my two cents - my completely stock Lortone Q66 (two six lb barrels) is running at around 27rpms.
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jimmie
starting to spend too much on rocks
Member since August 2021
Posts: 233
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Post by jimmie on Dec 13, 2021 16:02:37 GMT -5
I have a homemade one, 4 six pound lortone barrels. It runs at about 34 rpms. Works great. If it wasn’t so difficult I’d post pictures.
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,432
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Post by Wooferhound on Dec 14, 2021 6:41:31 GMT -5
I have 2 Lortone tumblers The 3 pounder runs at 60 rpm and the 6 pound runs at 30 rpm
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Post by jasoninsd on Dec 14, 2021 6:48:57 GMT -5
I seem to have gotten more into cabbing than tumbling, but nearly every time I go out hounding I seem to become a tumbler! (That really is a pretty cool homemade setup by the way! )
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hiswitness18
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Member since January 2022
Posts: 2
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Post by hiswitness18 on Jan 8, 2022 21:51:10 GMT -5
where do you buy the axel rod and bearing at?
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jimmie
starting to spend too much on rocks
Member since August 2021
Posts: 233
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Post by jimmie on Jan 9, 2022 6:43:22 GMT -5
I bought my saddle bearings off eBay. The rods I got from my steel guy. Just make sure you get matching , rods fit the bearings.
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badrock
starting to shine!
Member since January 2022
Posts: 30
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Post by badrock on Jan 9, 2022 9:12:12 GMT -5
About the RPM problem. My Lortone QT66 is turning at 44 rpm while my 3a is turning at 65. Therefore:
QT66: (44(RPM) x 7.5" (Barrel Diameter) x 3.14(Pi) x 60 (Minutes in an hour)) / 12 (Inches in a Foot) = (5,181 feet per hour) 3a: (65(RPM) x 4.5" (Barrel Diameter) x 3.14(Pi) x 60 (Minutes in an hour)) / 12 (Inches in a Foot) = (4,592 feet per hour)
Perhaps the near constant is the speed which the rocks are rolling within the barrel. If so, you could design your rock tumbler to travel at at speed of 0.98 to 0.87 mph? There are 5,280 feet in a mile.
PS. Caution. I did not double check my math. Trying to express an idea more than numbers. Also, maybe the correct dimension is the internal diameter and not the external diameter. This number might place the two distances closer together in theory. But, the tumbler works with the external dimension, therefore I did not take those measurements.
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Post by Rockoonz on Jan 9, 2022 13:47:44 GMT -5
There was a discussion quite awhile back that took it down to SFPM at the OD of the barrel, I can't remember if jamesp did the calculations or if I did. Roller OD and diameter determines that number, and barrel diameter doesn't change it. What I don't remember is whether different diameters and inside shapes of the barrels changes the optimum RPM, but I'm guessing it does. 1:10 pulleys (~172rpm) on a 1" OD rod is ~45sfpm, 2700sfph. That is what the base I use for 2 15# steel barrels or 1 40# steel barrel (hex shape) does now, and it works pretty good. I think smaller ones have a higher surface speed, but the barrel ID's are closer to round. If the same setup was on a 3/4" OD rod will net 37sfpm. The OD of the shaft makes the most difference. Shaft rpm would have to be increased to 225 to have the same surface speed, swapping 10" pulley for 8" gets you close.
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jamesp
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Member since October 2012
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Post by jamesp on Jan 10, 2022 8:09:14 GMT -5
Inches/second worked for me Rockoonz. Random speeds : 10 inch barrel at 20 rpm is 3.14 x 10 x 20 divided by 60 = 10.5 inches of linear travel per second. 6 inch barrel at 44 rpm is 3.14 x 6 x 44 divided by 60 = 13.8 inches/second 8 inch barrel at 36 rpm is 3.14 x 8 x 36 divided by 60 = 15 inches/second If an 8 inch barrel has heavy 1 inch thick walls then the effective tumbling diameter is 6 inches so: 6 inch barrel at 44 rpm is 3.14 x 6 x 44 divided by 60 = 13.8 inches/second Practical speeds for smallest and largest barrels. Big barrels should turn quite slow to achieve a healthy linear speed of say 10 to 12 inches/second 16 inch barrel at 18 rpm is 3.14 x 16 x 18 divided by 60 = 15 inches/second. In a big barrel like 16 inches diameter I would run it slower like 10 inches/second(12 rpm). And a smaller diameter barrel like 4 inches in diameter say 16 inches/second linear speed is acceptable.(about 70 rpm)
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Post by Rockoonz on Jan 10, 2022 9:35:37 GMT -5
Thanks jamesp I translated to SFPM and wrote it in my shop notebook for reference, my formulas in the spreadsheet/calculator I use for pulleys/rpm/belt length spits it out in FPM. For those who have to translate ips to fpm on the fly, ips/12=fps and fps*60=fpm, so ips*5=fpm for those who think faster in base 10 like me. If I have it right, I think I will try out one of my 2 speed swamp cooler motors on the base for the 40# or 2x15# barrels, pulley arrangement still TBD based on me finding something to slide over the .75 shafting that can withstand a loaded 40# barrel for more than one load, all versions of reinforced hose have failed so far.
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