Homebrew tumbler RPM

[cheese1566]

What is the "golden" RPM for a rotary style brass tumbler?

I read somewhere about 30RPM was the prime speed for brass.

What about polishing rocks?

Building a homebrew rotary tumbler that will use 6 gallon buckets and maybe a 30 gallon steel drum. It will have a quick adjustment design with optional pulleys to compensate for the various drum diameters. Also have an idea tinkering to use it as a rock tumbler.

[John Boy]

The RPM of the barrel is very important. Speeds that are too slow will not create enough friction between parts. The best results can be achieved at 28 to 30 RPM, depending on the work to be done and the size of the barrel. Greater speeds will result in a faster action, but a poorer finish. Slower speeds will take longer to do the job, but will be safer for large or delicate parts. When deburring parts, it is best to start at a low RPM to cut the burr instead of rolling it over. The RPM can be increased when this danger has passed. For burnishing, a higher RPM can be used.

Small barrels require faster speeds to equal the same amount of surface feet per minute as larger barrels. Faster speeds may be desirable for deburring parts, but these faster speeds may overcome the force of gravity and interrupt the constant even slide zone within the barrel, causing part impingement, pitting, or damage to the parts being processed. Instead of the parts tumbling, they may become airborne and get pounded or showered with heavy particles, causing impact damage. Where the part surface finish is not important and shorter cycle times are more desirable, this may be an acceptable process, but it is not the best use of the equipment. Continued use at a high RPM will shorten the life of the media by breaking it up faster or it may affect the inner walls or liner of the work chamber.
http://www.kramerindustriesonline.com/finishing-guides/barrel-finishing-guide.htm

[ept000]

Mine uses a 5 gallon bucket with four mixing paddles and turns at 30 RPM. Works great.

http://farm4.static.flickr.com/3375/3413787902_814e89f7fb.jpg

[yondering]

If you're making a vibratory tumbler, a cheap surplus fan motor that turns at 1120 rpm (or therabouts) works great. Just put an offset weight on the shaft, and mount it next to or underneath the tumbling media bucket. This works just as well as the commerial units, and polishes faster than the "rock tumbler" type.

[cheese1566]

Making a rotary...

I have a Hornady M2 tumbler for final polishing small batches.

:bigsmyl2: