rkp209
off to a rocking start
Member since June 2016
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Post by rkp209 on Jun 20, 2016 13:27:45 GMT -5
I'm making a brass/rock tumbler. My motor is a 1/2 hp and it turns 1750rpm's. The shafts are 1/2 rod with 1/2 ID heater hose on the with an outside diameter of 13/16 of an inch. The drunk is octagonal with 10" wheels. What would be the pulley sizes for my project?
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Deleted
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Post by Deleted on Jun 20, 2016 14:38:49 GMT -5
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Deleted
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Post by Deleted on Jun 20, 2016 14:40:16 GMT -5
You will need to measure the OD of the heater hose.
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Post by johnjsgems on Jun 20, 2016 16:08:27 GMT -5
If only Ben Dover was still in ground control. He could figure it out.
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Post by johnjsgems on Jun 20, 2016 16:38:02 GMT -5
OK, I think I figured it out. The shaft speed formula is:
motor speed X motor pulley diameter divided by driven pulley diameter.
If you want 20 rpm barrel speed use a 1.5" motor pulley and a 16" driven pulley. 1750 X 1.5 divided by 16 = 164.06. 164.06 is the barrel shaft speed. Multiply that speed by 1.23 and divide by 10 for 20.18. Barrel actual inside diameter would change results. Just change pulley size until you get the desired barrel speed. Too fast only works for roughing. For barrel speed check manufactured tumblers with same size drums. I'm guessing brass could turn faster than rocks.
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Post by Drummond Island Rocks on Jun 20, 2016 20:29:20 GMT -5
Hmm seems like Microsoft excel would work good for something like that. Chuck
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Post by spiceman on Jun 20, 2016 20:33:09 GMT -5
There are many websites that calculate all that for you. Google it and input your motor speed and what you want for output(rpm). You can play around with it to find the best pulley sizes that works for you.
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Post by johnjsgems on Jun 21, 2016 18:40:45 GMT -5
Oops. 13/16" is .81. Are the barrels 10"? Not sure by OP. Driven shaft becomes the "drive pulley" to turn barrel.
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Post by Rockoonz on Jun 21, 2016 22:15:32 GMT -5
Chuck, do you have the link to that spreadsheet? It was in a thread here and I saved it a couple PC's ago.
When I compared factory tumblers a few years back the surface speed at the rollers was close to the same for all of them. Rpm is unimportant, the speed of the surface the rocks are rolling on is the ticket.
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Post by Drummond Island Rocks on Jun 22, 2016 5:39:32 GMT -5
Chuck, do you have the link to that spreadsheet? It was in a thread here and I saved it a couple PC's ago. When I compared factory tumblers a few years back the surface speed at the rollers was close to the same for all of them. Rpm is unimportant, the speed of the surface the rocks are rolling on is the ticket. I made that spreadsheet when I built my tumbler a few years ago. PM me your email address and I can send it. Chuck
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jamesp
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Post by jamesp on Jun 22, 2016 5:50:26 GMT -5
I'm making a brass/rock tumbler. My motor is a 1/2 hp and it turns 1750rpm's. The shafts are 1/2 rod with 1/2 ID heater hose on the with an outside diameter of 13/16 of an inch. The drunk is octagonal with 10" wheels. What would be the pulley sizes for my project? 10 inch barrel ?? 1750 RPM X small pulley/big pulley X .81/barrel diameter Do the divisions first, then the multiplications. Reduction #1 = small pulley/large pulley are the unknowns. Reduction #2 = shaft diameter/barrel diameter, which is fixed at .81/10 inch barrel = .081 reduction in speed assuming 10 inch barrel. Such a tumbler is a double reduction machine. so a fraction times a fraction times the RPM A good start is a 2-3 inch motor pulley and an 8-12 inch large pulley. 1725 X 2"/10" X .81/10 inch barrel = 1725 X .2 X .081 = 27.9 RPM 1725 X 3"/10" X .81/10 inch barrel = 1725 X .3 X .081 = 41.9 RPM 1725 X 2.5"/10" X .81/8 inch barrel = 1725 X .25 X .101 = 43.5 RPM Most tumbler shafts are 1/2" to 1" For fractional HP motors 1/4-1/3-1/2 Most motor pulleys are 2"- 3" Typical tumber large pulleys are 10" - 15 " A 1/4 HP will easily turn 40 pounds at 50 RPM. A 1/2 HP will use a good bit of electricity. I like A/C 110VAC fan motors-some of them are 1/6 and 1/8 HP at a slower 1080 RPM. Cheap to run. Smaller pulleys... And have had one run a 40 pound barrel for years. Pay for itself in one year versus that 1/2 HP. For a 10 inch barrel I would limit speed to 30 RPM for rocks, brass does not care. Better is 20-25 RPM for rocks, 10 inch barrel. so 2" motor pulley and 10 inch large pulley. or 2.5" motor pulley and 12" large pulley. Cheaper to go with small motor pulley so you can use smaller large pulley. If you had to use a 4 inch motor pulley: 1725 X 4/20 X .081 = 27.9 RPM, but who wants to spend $50+ on an 18- 20 inch pulley. And such a big pulley is an albatross.
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grayfingers
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Post by grayfingers on Jun 22, 2016 6:54:30 GMT -5
I built this tumbler for 2, 12 lb. Lortone barrels. I think the barrels are around 7" diameter. It rolls them at 35 rpm.
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Post by Deleted on Jun 22, 2016 8:55:10 GMT -5
I built this tumbler for 2, 12 lb. Lortone barrels. I think the barrels are around 7" diameter. It rolls them at 35 rpm. Work of art
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jamesp
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Post by jamesp on Jun 23, 2016 2:35:10 GMT -5
I built this tumbler for 2, 12 lb. Lortone barrels. I think the barrels are around 7" diameter. It rolls them at 35 rpm. Stone cold bullet proof. Your machine is as efficient and reliable as they get Bill. Auto grade belt, bearings w/grease fittings, fractional HP motor, quiet wood base, industrial grade sheaves, heavy solid shafts. Manufacturers avoid this design partially because of product liability. They have to spend money covering up the nip points of the big pulley. Underwriters give them hell on nip points. This is why home made tumblers make sense. Just watch fingers. Curious, what are the stud like rods sticking out of the pillar block bolts ? Loosing sleep on those. And bolt studs, are they mounted in the wood- enigmatized ? Speed calc on that one easy. I think Lortone barrel is 7.5 ?? 2/10 X .75/7.5 = .2 X .1 X 1725 = 34.5 rpm. Barrel exactly 10 times bigger than shaft. 1/10th reduction. sickening, planned and sinister, slicker than greased lightning note posi-traction on other end, both shafts driven to avoid slippage. My albatross has 1.5 inch shafts forcing me to buy a $60 20 inch diameter pulley to get ~30 RPM.( double shaft diameter and have to double pulley diameter for ~30 rpm) That's what happens when you scrounge scrap and don't think ahead. 20 inch pulley made table top tumbler difficult. Chain reaction. Add 40 foot v-belt.
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grayfingers
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Post by grayfingers on Jun 23, 2016 7:32:02 GMT -5
jamesp and @shotgunner , thanks for the kind comments. It was a easy build for someone like me who is not as savvy with drawings and designs as guys like you. Only tools required were basic. I enjoy James' builds, with the little roller guide wheels, gear boxes and such. The photo of the bolt was taken as I was lining everything up for final tightening, put it all together and ran the belts/rollers by hand to get everything "settled in" before tightening. The bolt is a pin anchor bolt, I stumbled across them at the hardware store when looking for regular bolts to either screw or glue into the 2"x8"s. So, I just had to tap the pins the rest of the way in to swell the bolt shaft and tighten the nuts. Can remove them if needed. I used a clamp on dowel drill guide to drill the holes for the bolts so they would be true. The motor and the big sheave came from a greenhouse box fan, got a spare motor too. The tumbler gets positioned so as to keep the big sheave away from the 'reach zone', never have come close to getting tangled up in it though I see why it would be a liability for a manufacturer. The area under the motor deck is nice for storage...
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jamesp
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Post by jamesp on Jun 23, 2016 8:19:51 GMT -5
Well now those pins are not sticking up out of the studs holding the pillar blocks in these photos. Where'd they go ? Looks like you ground them off. Could align the right pulley so that both set screws are facing 12 o'clock ? grayfingersNever seen such anchors for wood, just concrete.
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grayfingers
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Post by grayfingers on Jun 23, 2016 9:55:57 GMT -5
jamesp , The bolts I got had a recess for the head of the pin,tapped in flat, but I think one could get something under the lip to pry them back up if needed. For all I know, the bolts may have been for concrete, I had never seen them before either. It is nice that the belts are standard Gates sizes to be found anywhere should one ever wear out. So are you teasing about the set screws both being aligned to 12 o'clock, or would that balance them more evenly? It is very quiet, only sound is the dull surf of the barrels rolling. I built it for two reasons, to be able to spin twice as many rocks as my actual Lortone, and weight concerns. I found that if I fill the barrels 3/4 full with the addition of lots of smalls for filler which gives me the best grind they weigh much more than 12 lbs. Was concerned about the little motor on the Lortone unit frying...
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Deleted
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Post by Deleted on Jun 23, 2016 10:00:43 GMT -5
Well now those pins are not sticking up out of the studs holding the pillar blocks in these photos. Where'd they go ? Looks like you ground them off. Could align the right pulley so that both set screws are facing 12 o'clock ? grayfingersNever seen such anchors for wood, just concrete. Well, it seems they work in wood too! If you are gonna go to all the trouble to paint everything all purdy, yeah, maybe ya should get all the pulleys lined up in sync too... grayfingers
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jamesp
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Post by jamesp on Jun 23, 2016 11:02:39 GMT -5
grayfingers wood hard stuff, allows anchor bolt to flare. Gracious. Yes teasing about the alignment and the paint was a bit off on the left pulley. Jealous of the order and cleanliness. Mine looks like the inside if a cement mixer. Lortone barrels freak me out as they are so quiet as opposed to PVC. One time I had a barrel leak and a blob of dried slurry caked on the the two end pillar blocks. I let it run for months. Finally a squeaking sound. Surprisingly it was the outer race of the bearing spinning in the self-alignment socket. The bearing was fine. If you can't see your pillar blocks because they have an inch of slurry cake on them you are not very tidy. Next time a 21 year old bikini next to the tumbler please.
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Post by johnjsgems on Jun 23, 2016 16:56:06 GMT -5
Nice tumbler. For the sake of argument, if the "load" is 6 amps, hp doesn't make much difference. 1/3 hp will draw 6 amps, 1/2 hp draws the same. Only difference is lower hp may be maxed and larger at 2/3 full load.
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