jamesp
Cave Dweller
Member since October 2012
Posts: 36,548
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Post by jamesp on Mar 14, 2014 15:04:24 GMT -5
Chuck is so right. You want positraction for sure. Pretty machine vugs. I am happy with having the slow speed. Coarse grind is a long demanding process. Putting a 220, 500 and polish finish is way quicker of a process. And the polish is certainly finicky if things are running too fast. The reason (i am guessing) factory tumblers are one speed is for cost. So they seem a bit slow for the coarse grind on agates which is probably the most common thing tumbled. And I tumble a hard form of agate so i made the high speed deal. It saves a lot on electricity i guess. But target was a good shine. so i am faster than a factory speed on coarse and slower than factory on finish. Again, that rig looks real professional.
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Post by Drummond Island Rocks on Mar 14, 2014 18:40:57 GMT -5
one more thing ... I didnt see any barrel guides in that photo and those are important too. A barrel running up against a pillow block bearing will do some damage. I created an excel document that will do all the math on barrel rpm's. you can change any number in the document and it all updates. So if you change the roller shaft diameter from 3/4 to 1" the end rpm's adjust automatically. If you want a copy PM me. Chuck
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,548
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Post by jamesp on Mar 14, 2014 23:37:53 GMT -5
The tumbler i posted is slightly tilted down hill so that the guide rollers are only on one(the down hill) side. Never had any trouble with grit accumulation.
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vugs
starting to spend too much on rocks
Rockbiter
Member since February 2014
Posts: 225
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Post by vugs on Mar 15, 2014 18:26:35 GMT -5
thanks guys. my tumbler will have some bearing roller guides.. one on each end. also the shafts have rubber tubing around them for traction. the barrels will be rubber lined to reduce noise and i may mount the motor on some anti vibration gel washers from Misumi. i was having too much fun designing it so its probably overbuilt but she should tumble nicely.
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Post by cpdad on Mar 15, 2014 19:36:15 GMT -5
i gonna tell you what i did ...and i want to say actually everyone that that has posted is correct in one way or another....great group for sure. ...me just a dumb redneck . i have 3...3lb double barrel tumblers....they run at 60 rpms....i use this rpm for rough...whether 47/70...60/90..i also use this rpm....for 120/200. at the higher rpm's....i usually find all my fractures and broken stuff during this stage....most stuff gonna fracture during this time....at 60 rpm. varible speed motor is the way to go...but i did something a little different...i installed a dimmer switch on my 60 rpm tumblers. i just change the rpm as i feel like it...i can roll at 15 rpm for obsidian...or 33 rpm for agates. just put a mark with a sharpie on your barrel....you can count the rpm's. i'm drunk going to bed....kev.
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vugs
starting to spend too much on rocks
Rockbiter
Member since February 2014
Posts: 225
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Post by vugs on Mar 21, 2014 0:51:10 GMT -5
thanks for the tip Kev.
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Post by Rockoonz on Mar 21, 2014 15:42:26 GMT -5
one more thing ... I didnt see any barrel guides in that photo and those are important too. A barrel running up against a pillow block bearing will do some damage. I created an excel document that will do all the math on barrel rpm's. you can change any number in the document and it all updates. So if you change the roller shaft diameter from 3/4 to 1" the end rpm's adjust automatically. If you want a copy PM me. Chuck Chuck, your calculator is awesome, even works great with open office calc instead of MSexcel. When I put the new tubing over the roller shafts I will know exactly what I need to change to get the best RPM. I will also be installing a 2 speed HVAC motor to see how the slower speed works for polishing some materials.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,548
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Post by jamesp on Mar 22, 2014 4:14:50 GMT -5
After 2 years of running full time I have noticed a squeaking sound coming from the high speed self centering pillar blocks when the air is below 40F. Finally figured it out. The grease is getting thicker/harder in cold temps and the spherical outer race is spinning occasionally in it's socket due to the friction in the actual bearing from cold grease. The bearing is OK. The PVC barrel has a couple of bumps in it and allows the outer race to slip in it's socket when it hits the bump. One of the high speed barrels has cupping marks all the way around it creating a vib/rotary effect. Could be a vibrotary tumbler situation. hmmm.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Mar 25, 2014 17:31:24 GMT -5
thanks james, i like the variable speed concept. i talked my buddy into welding up the tumbler frame so im in the planning stage trying to gather info. Use wood, it's quieter.
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mitslplik
off to a rocking start
Member since January 2019
Posts: 1
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Post by mitslplik on Feb 25, 2019 3:29:18 GMT -5
How do you determine hours of rotation per grit size?
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jimaz
spending too much on rocks
Member since July 2018
Posts: 463
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Post by jimaz on Feb 25, 2019 12:03:46 GMT -5
That’s quite an interesting setup! Do you use the treadmill while tumbling? Most people run rotaries from a week to two weeks regardless of the grit size. May run a little shorter for soft stones.
Also,welcome to the forum from southern Arizona.
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noahnation
off to a rocking start
Member since April 2022
Posts: 1
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Post by noahnation on Apr 1, 2022 18:02:28 GMT -5
Hi all I'm wondering how fast rpm wise I should gear this tumbler I just got it's about 24 inches in diameter and three feet wide. It was an industrial tumbler I'm converting into a rock tumbler and not sure how fast it should go. I can't figure out how to upload an image haha, thank you for all your insight!
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Apr 1, 2022 23:48:19 GMT -5
I run a double barrel set made of 12" pvc a foot long each, 5 gallon capacity each. Running them at 12-17 rpm [variable speed pulley on the motor] has worked out well for me. I run a mix of mostly pet. wood and agate from pea size to three or four pound pieces. I would think half to 2/3 the speed I run mine at would be a good starting point, or in the 6-10 rpm range.
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