So one of my friends who collects a lot of brass and is my supplier for range brass, saw my post on a different thread and asked me to help him build a brass tumbler for him to use.
I built this, just got a used tread mill for free off of Craig's list. Looked for a larger one so it had plenty of power. Bolted a couple of 2x4s to my bench, ran some lag bolts through the rollers from the tread mill, used the motor and controller, also screwed to the bench and had what i needed for the price of the 8" sewer pipe an end cap, adapter and rubber cap. It didn't run perfectly true so I put a bearing on a dowel to keep the tumbler from running off the rollers. still need a cover for the controller and the motor fan. It's not OHSA approved and it's not pretty but I've run 14-3-1/2 gallon buckets of brass through it and it works great. I bought 20# of over-sized pins, (don't remember where). I can tumble as much as I want to lift, up to about 2 gallons of brass. I built it in my shed so I can keep the noise away from where i'm reloading.
I forgot, I also had to add fins to the inside of the tub, just some 2" pipe cut in 4 ths length wise and bolted to the tub before the caps were glued into place. A Goggle search for DIY brass tumbler will get you most of the info. This is not an original idea. I just used the tread mill to get my parts from so I could build it on the cheap and make it easy.
Since I have only done it one way, I was wondering if others have experience that might make my next build better. His would need to to be portable, unlike mine. I've looked a lot online but am asking for personal experience. Either first hand or through interactions with friends.