|
Post by fantastic5 on Nov 13, 2014 15:45:46 GMT -5
By looking at the chart, with the 1.5" motor pulley and 10", my 6 pound barrel should turn around 25 rpm. Right? My top story of the tumbler will be running three pound barrels. If I put a 2" pulley on the drive roller on the lower level and a 3" pulley on the upper level drive roller, the 3 pound barrel should slower than 50 rpm. Right? My brain hurts. The way the pulley's slow things down didn't seem to make sense to me. I trusted the math, but it really bugged me that I couldn't 'see' it. To me a bigger pully on the motor should slow everything down not speed things up. So I actually drew everything out and imagined the speeds at each point, center of the motors drive shaft, outer edge of the pulley where the belt runs up and up to the larger pulley and so forth. Took me a little bit, but did have the ah-ha moment when it all clicked.
|
|
billg22
spending too much on rocks
Member since November 2011
Posts: 451
|
Post by billg22 on Nov 13, 2014 16:52:15 GMT -5
Thanks Ann, I'm going to try the 1.5 inch motor pulley and the 5 inch roller pulley just to get tumbling. I think I'll plug in my old tumblers to check their rpm's. I guess I'll get close and go from there. Thanks for the help and inspiration. -Bill G
|
|
cobbledstones
spending too much on rocks
Member since January 2014
Posts: 482
|
Post by cobbledstones on Nov 14, 2014 10:40:28 GMT -5
I am running my tumbler FAST. I can always change my pulley sizes to slow things down, but I wanted to push the envelope and see what happens. I have a 1 1/2" pully on the 1/6 th hp motor (it's drive shaft is 1/2"). It goes to a 5" pully on the lower shelf. Math looks like this: 1725 RPM X 1.5/5 X .625/6 = 54 RPM That is with 1.5" motor pulley, 5" pulley, 5/8 inch shaft and 6" PVC barrel This then runs up to my top level by way of a 2" pulley on the bottom 5/8" rod to the 2/5" pulley on the top 5/8" rod. 323 RPM x 2/2.5 x .625/8" (6# barrel) = 20 RPM 323 RPM x 2/2.5 x .628/4" (3# barrel)= 40 RPM Now that is the math, but when I actually count the RPM's of the 6# barrel it is running closer to 25. It has done a great job rounding agates and I have finished the first batch and moved it into the vibe. The coral is MUCH slower and really chewing through the grit. I have enough grit to re-charge tonight, then I am out until a shipment comes in. I actually haven't run anything on the lower shelf as I haven't yet constructed the PVC barrels. I didn't see a reason to do that until I have bulk grit. Hope this helps. Ann Ann, RPM calcs could be slightly off for 2 reasons 1) the shafts in contact with the barrels aren't 5/8 anymore, but slightly wider because of the hose you put over them (this speeds up your barrels) 2) To get a perfect outcome, one should use the 'datum diameter' of the pulley. This number is slightly smaller than the measured diameter and changes depending on the belt type (A or B). Not a big deal under most circumstances, but if there is a very small pulley somewhere it can make a difference. see www.surpluscenter.com/Power-Transmission/Pulleys/Finished-Bore-Pulleys/2-45-O-D-1-2-BORE-1-GROOVE-PULLEY-1-BK24-A.axd for an example.
|
|
|
Post by Rockoonz on Nov 15, 2014 15:43:51 GMT -5
The surface speed in SFPM is a better target than RPM. Once you have set the surface speed of your rollers to the speed you want it should work for every size of barrel. Chucks Excel calculator setting above would net 50.8 SFPM, which translates to 50.08 RPM on a 3.875 barrel and slower on a larger barrel. Theoretically the same setup should work for all barrel sizes, the only difference being the distance between the rollers on smaller and larger barrels. The steel barrels with the hexagonal liners may require a different SFPM than a smooth round barrel, but once you determine the best speed it should translate over to al barrels of that type.
|
|
|
Post by Drummond Island Rocks on Nov 15, 2014 17:12:30 GMT -5
The surface speed in SFPM is a better target than RPM. Once you have set the surface speed of your rollers to the speed you want it should work for every size of barrel. Chucks Excel calculator setting above would net 50.8 SFPM, which translates to 50.08 RPM on a 3.875 barrel and slower on a larger barrel. Theoretically the same setup should work for all barrel sizes, the only difference being the distance between the rollers on smaller and larger barrels. The steel barrels with the hexagonal liners may require a different SFPM than a smooth round barrel, but once you determine the best speed it should translate over to al barrels of that type. Very true. I have found I can run my 3 pound and 12 pound barrels on the same exact set of rollers together and they both run at the same speeds they do when I have them in their original lortone tumblers. I consider my homemade tumbler to running right when the RPM matches the equivalent store bought lortone setup. Chuck
|
|
billg22
spending too much on rocks
Member since November 2011
Posts: 451
|
Post by billg22 on Nov 17, 2014 14:12:45 GMT -5
I had some time to work on my two story tumbler. Frame is built, bearings placed, rollers in garden hose and pulleys attached. Just waiting on the delivery of the motor. I lucked out and found a source for pulleys, Ace Hardware. Test runs will work out the pulley ratio.
I guess I'll slap some paint on it and make it look good. Waiting . . . . . . . .
|
|
Deleted
Deleted Member
Member since January 1970
Posts: 0
|
Post by Deleted on Nov 17, 2014 14:56:24 GMT -5
I'll vote for purple. All rock tumblers should be purple...........
|
|
billg22
spending too much on rocks
Member since November 2011
Posts: 451
|
Post by billg22 on Nov 17, 2014 17:10:38 GMT -5
Scott, as long as there's some purple in the Home Depot oop's paint section. I figure a couple of those 50 cent rejects should do it.
|
|
|
Post by Drummond Island Rocks on Nov 17, 2014 17:48:49 GMT -5
I had some time to work on my two story tumbler. Frame is built, bearings placed, rollers in garden hose and pulleys attached. Just waiting on the delivery of the motor. I lucked out and found a source for pulleys, Ace Hardware. Test runs will work out the pulley ratio. I guess I'll slap some paint on it and make it look good. Waiting . . . . . . . . Ace hardware was my pulley and v-belt source too. My store did not stock the pulleys I needed but free shipping to the store so I ordered it all online and picked it up at the store a few days later. very fair prices. Chuck
|
|
billg22
spending too much on rocks
Member since November 2011
Posts: 451
|
Post by billg22 on Nov 18, 2014 13:14:43 GMT -5
Chuck, Ace prices work out over some ebay prices because of shipping prices. That and it's not too far from home.
|
|
hornseeker
spending too much on rocks
Member since January 2014
Posts: 268
|
Post by hornseeker on Feb 9, 2015 17:28:15 GMT -5
The pictures need to be put back up!! or am I the only one with a lot of red x's
|
|
matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
|
Post by matt2432 on Apr 25, 2015 14:44:17 GMT -5
The pictures need to be put back up!! or am I the only one with a lot of red x's You're not the only one, what happened to the pictures?
|
|
|
Post by fantastic5 on Jun 25, 2015 18:56:46 GMT -5
The pictures need to be put back up!! or am I the only one with a lot of red x's You're not the only one, what happened to the pictures? Sorry it took me so long to see this in my notifications. Not sure why Facebook changed the URLs for the pictures, but I've gotten them fixed. I've made a few modifications. I've added a direct drive to both levels (rather than just letting the barrel turn the second rod. I've also found these link belts: I like these, they are adjustable which takes the guess work out of getting the right size belt.
|
|
matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
|
Post by matt2432 on Jun 25, 2015 19:15:12 GMT -5
Thanks for fixing the pics!
|
|