I finally put this project together after moving on to shooting 8x20 and could not bear manually rotating the drum.
Basiclaly it is made up of a roller base with 4 Rigid Wheels, a motorized arm with 2 wheels and a Arduino Uno box.
More details on the parts and components at http://sgwetplate.com/2016/10/diy-ro...ilm-processor/




The roller base with 4 Rigid wheels
I connected the 2 pieces of plywood using 2 brass rails (they were from a forsaken camera project). They are locked down using 1/4" bolts and nuts. This will allow me to adjust the distance between the 2 rolls of wheels for catering to drums of different diameters. At this point the drum should rotate smoothly and evenly by hand.


The motor and the shaft coupler
For now I am using a 12V 30 rpm motor. To mount the 3/8" threaded rod (again another piece I have sitting around) , I use a flexible shaft coupler which has a one 6mm hole what will fit the motor shaft while the other end is a 10mm hole that fit the 3/8" rod.