Based on the good reviews here on the harbor Freight tumbler I bought one. The two drum unit. It was defective right out of the box. Grommet on wire at motor, plastic cooling fan on motor. Other issues I cant remember detail on right now but it would not run for any length of time without stopping and plus it just looked like it was not worth anywhere close to what I paid so I took it back and ordered the two drum Thumblers Tumbler which does work right out of the box and is obviously higher quality. I should not have to dick with something I just bought to get it to work.
Others have had good experience with the HF unit but not me. I like HF stuff generally and buy there if the quality is good and price is right.
I'm having problems tumbling zinc pennies in solution of water, dish soap and CLR. Seems maybe the rotten zincs react and outgas enough to pop the lid off of the Thumbler drum after a short while. No problem with clad quarters dimes, nickles which tumble in a separate drum.