An Improved Version of the Tank Tumbler
Robert Evans from Oregon, built a much sturdier and nicer version of my Tank Tumbler. He did a couple of things differently to address some of the mistakes I made. He mounted his motor on a third plate, and then ran the drive shaft through a bearing on plate number two. It made the motor/drive shaft connection a lot easier and very solid.
Instead of all-thread for the idler rollers he used 1/2" rod and bearings to mount the ends. Then when he put a tank between the rollers and noticed that the idler rod flexed a bit so it now has a beautifully designed support bracket/brace which ties both of the 5/8 side all-threads to the 1/2" idler rod.
See the pictures that Robert was kind enough to send me, and I think you'll agree, its a much improved model!
He spent a lot of time on the drive roller, and claims he was fixated on a nice solid 1.5" rubber roller which simply wasn't available. In the end he went to Fred Meyers and bought two wood cooking rolling pins complete with a 5/8 hole down the center, glued them to a 5/8" steel rod and mounted them in the bearings. Next stop was his neighbors lathe where at the cost of only a couple of beers, his good neighbor turned the glued rolling pins down to 1.4" and then Robert pulled a bicycle inner tube over the wood pins. Presto, he had a 1.5" rubber coated drive shaft! An elegant and inexpensive solution... and most importantly it worked well and made Robert happy!
The one thing Robert would have liked to have done differently was to eliminate the mounting bearings on the 1/2" rod. His idea required a 1/2" or 5/8" die so he could cut threads on the end of the rod and just bolted the rods to the end plates like Boydski's tumbler has. Unfortunately, neither Robert or his friends had 1/2 or 5/8 dies, so he chose to use bearings instead.
Some folks might wonder why they can't just glue the rolling pins onto the shaft and let it rip. The obvious reason of course is that the 2" pins are too large and would increase the tank RPM too high. The less obvious reason is that the 5/8 inch holes through the rolling pin are not drilled exactly parallel with the outside surface which would cause the tank to wobble if the pins were used in their original form.