Rock tumbler bearings

Hi all,
Having been busy with other things, I haven't started to build my stone
polisher yet, but I've had chance to ponder the design a little. Often I
like to do this because I find after a week or two a smart idea will
come into my head, which I would otherwise have missed.
Anyway, I have a small problem with bearings. I intended to use
self-aligning ball races in pillow blocks, but it turns out that the
pillow block for a 1/2" diameter shaft is 5" long! So I can't get the
shafts closer than 5" apart unless I stagger the pillow blocks, which
will look messy. I want about 4" between the shafts, and I might make
this distance adjustable to allow different barrel sizes to be used on
the same machine.
Pillow blocks don't seem to be available for shafts less than 1/2"
diameter. I don't have access to a milling machine, so I can't make my
own "double pillow block" to carry two ball races. One idea I've had is
to use rod end bearings (as used in pneumatic cylinder linkages etc).
These could be attached to a base plate with a single bolt, provide the
self-aligning feature, and to cater for the rotation I could press a
bronze bush into the eye. I've checked and I can get components of the
right dimensions to make this work, but my local bearing supplier didn't
want to recommend it because the idea was unconventional.
What do people think? Will rod end bearings with a bronze insert stand
up to continuous use in a rock tumbler if I keep them clean and well
lubricated? Any thoughts would be much appreciated.
Best wishes,
Reply to
Christopher Tidy
Loading thread data ...
You can get inexpensive ball bearing pillow blocks with pressed steel housings that are only 3-5/8" long. See McMaster p/n 5913K41 as an example or download the .pdf on this page for more variations.
formatting link

Ned Simmons
Reply to
Ned Simmons
Hmm. What if you mounted one pair of pillow blocks right side up and the other ones upside down? Get 'em real close that way, but you'd have to modify your design thinking a little.
Actually, you don't have to use pillow blocks. You can used flanged bearings like this one:
formatting link
but on the sides of your tumbler, not on the floor. Again, a little different thinking.
Reply to
Grant Erwin
Stand the pillow blocks on end and you can get em pretty darn close together. Wedge em apart for spacing. And no the brass bushings won't take the 24+ hour runs a tumbler would need for long.
Reply to
I think you're limiting your search for bearings too much. MSC has 1/2" pillow block bearings ranging from 1.126" to 5" overall length. The smaller ones have a stamped steal pillow instead of a cast one. They also have a bearing block with a 2-bolt flange that could be bolted to a riser plate on each side instead of using the pillow blocks.
formatting link
Or if you happen to have quick and inexpensive access to the type you were originally talking about you could weld a vertical bar with 2 holes in it to your base plate and mount the pillows on it with the bolts going all the way through both pillows. I'm not sure how much closer that would put them but it should help quite a bit.
Best Regards, Keith Marshall
"I'm not grown up enough to be so old!"
Reply to
Keith Marshall
I think I would make my own double pillow blocks out of wood with bronze sleeve bearings. W.W. Grainger sells bronze bushings for about $3 for three bushings. If you have access to a drill press you could drill both blocks at the same time so both blocks have exactly the same spacing and height. The bushings may not last forever, but would last pretty long. Bronze is what the hobby tumblers use. And replacing them several times would be cheaper than buying sealed ball bearings.
Reply to
| Hi all, | What do people think? Will rod end bearings with a bronze insert stand | up to continuous use in a rock tumbler if I keep them clean and well | lubricated? Any thoughts would be much appreciated. | | Best wishes, | | Chris
Do a little research into wood bearings. They just happen to be the very best type of bearing for abrasive applications. There's several options. The real beauty of it is that you can even make them yourselves!
Reply to
carl mciver
That's what I use on my sh*t shaker (compost screening plant) I used blocks of oak(?) from pallets faced and bored on a lathe faceplate. The 1/4" throw eccentrics run in pairs of these and are greased through grease nipples mounted to hollow 3/8 cap screws threaded into the wooden bearing - this was to increase the tapped hole strength in the wood - the nipples blew out without the hollow cap screw adapters. At ~600 RPM these bearings work great but need a bit of clearance. Gerry :-)} London, Canada
Reply to
Gerald Miller
How about taking a block of UHMW and drilling two holes in it at whatever spacing you desire. With a moderate load UHMW will last a long time and when it wears you can just drill two more holes. If you have a heavy load you can use nylon for better wear resistance.
Reply to
Wood bearings were common in windmills. Just make them a little longer. Check older machinists books for info on wood bearings, types of wood, lubrication.
Reply to
Chris, Consider using two parallel shafts (length to suit length of drum (s) you are planning to use, but mount two rubber "tires" on each shaft, one on each side of the barrel at the bottom and one on each side of the barrel at the top. If they are spaced right, and if the tires are of sufficient diameter, many different size drums can be placed on the tires and still be rotated. The rubber tires will dampen the noise a bit, provide good "traction" for the drum, will last forever, and will eliminate the need for moving the shafts apart or closer for different size drums. Just a thought.... HTH Ken.
Reply to
Ken Sterling
On Tue, 28 Jun 2005 02:14:51 -0500, the opaque "bw" spake:
Lignum Vitae wood has been used on boat propeller and rudder shafts for centuries now.
Reply to
Larry Jaques
Sorry for the slow reply to this thread. I immediately thought of Lignum Vitae when someone mentioned wood bearings. An old schoolteacher told me if was used to line sterntubes years ago and it stuck in my mind. Is it readily available and affordable? I'd be interested to experiment with it.
By the way, the reason I didn't suggest using those "egg shaped" bearings (the kind with two bolt holes parallel to the shaft) is that no one will supply the to me at a sensible price in England. We can't get prices anywhere near to McMaster's for a lot of stuff!
I might be able to get regular pillow blocks cheaply enough, but I don't really want to mount then vertically or with one upside down. I think it'll spoil the looks of my tumbler. Maybe I should wait till I get a milling machine, but that could well be a few years!
Must go - supposed to be going on holiday in 4 hours!
Thanks for the suggestions,
Reply to
Christopher Tidy
Try the NSK "Silver series " bearings. They make pillow block bearings and 2 hole flange bearings that are more compact then the usual industrial size blocks.
Reply to
Tom Miller

Site Timeline

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.