Speed of a tumbler drum?


September 5, 2011, 09:15 PM
I'm building a dry tumbler for my brass. Wondering what the speed range (RPMs) is of commercial tumblers and their diameters so I can convert that info for the 14" diameter steel drum I'm using.
I looked at commercial tumblers and for their tiny size, they sure are expensive. I have a couple small steel drums with gasketed, clamping lids, some non swiveling casters for it to ride on. I plan on coating the inside of the drum with construction adhesive or similar to reduce noise and give some grab. I may even give it grooves with a notched trowel or glue cross bars on the inside.
I plan on using an AC gear motor, pulley and V belt from McMaster Carr which will cost less than half of the commercial tumbler I was looking at and about 20% the price of the RCBS unit.
I need to choose the speed of the gear motor and size of the pulley so I can approximate the speed of commercial units.

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September 5, 2011, 10:00 PM
My Thumlers tumbler is running at 30 RPM. You will need something inside to break up the rolling to polish better.. Look inside a dryer and see how this works. I would use small paddles that were made of a rubber like material or they will just wear away. Use 6 not 3 like a dryer or it will be really noisy.

September 5, 2011, 10:23 PM
What's the diameter of the drum? I want to get about the same surface speed. With a larger diameter drum I'll need fewer RPMs.
Not sure what I'm going to glue to the inside yet for paddles.

September 5, 2011, 11:03 PM
I used wooden slats & bolted em in , & frogs rite on useing 6 , 3-4 will sound as if yor drying tinker bells !!!

I used a sealable 5 gal bucket & laid it on rods mounted on pillow block bearings , final rpms was 34 1/3 , it was long enuff to fit 2 buckets on it , 1 with corncob ,1 with walnut .

I sold it to the shooting club I shot uspsa at , it`s still runnin .

September 6, 2011, 02:16 AM
Make it with an acrylic top so you can watch the cases tumble.
I have done a lot of tumbling with nothing but a round drum. Worked well enough for me.
The main thing is NOT to rotate at more then 50 RPM.

September 6, 2011, 02:23 AM
If you use plastic/vinyl for the paddles, it'll be quieter. If your spiral them slightly, your brass will get more polishing/rev. .

September 6, 2011, 04:36 PM
Thanks all.
My drums are already on hand. I got them from my old plastics company a few years back with this project in mind. Found four fixed castors, the frame will be wood and the gear motor will sit on a hinged plate under the drum with the V belt looped over the drum for direct drive and the weight of the motor will provide tension on the belt.

September 6, 2011, 07:28 PM
If there that big 24"-36" in dia. I`d start with a 2" pulley on the motor, motor is 1340 rpm ????

September 6, 2011, 07:48 PM
No, the motors have built in gear reduction and range in speed from 1 to 200 rpm.
A 2" pulley and a 14" drum will give about a 1:7 rpm reduction, so if I want about 20 RPM I would choose the 150 RPM motor.

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