1. Torque ratio to drum size. Intuition tells me that like a car wheel, a larger diameter requires more torque to drive. I'm trying to figure out what formula would work for determining motor specs. I'm also assuming different grit produces different friction which would be part of the equation.
2. Gear reduction. What is the most cost efficient way to achieve a good gear reduction? The reason I ask is that the smoothness of the feed will be critical to success. Most designs I have found online involve hand feeding, but I'm gunning for a power fed solution. Is a worm drive going to give me any advantage over simple pulley differentials? I was loosely considering a garage door opener which should have a gear motor in it, but I'm also unsure of what torque I need to drive the belt.
3. Drum specs. Is there a particular grade of aluminum pipe that might be sufficiently round, and have consistent wall thickness that it could be used, and then trued up on the machine? From what I have read, most people have used MDF, or plywood laminated drums with a solid axial. This would be very time consuming to make but cost effective.
4. Drum weight. What effect does the drum weight have on performance in this sort of application? Is there any advantage to a heavy drum?
5. Table alignment. It would be critical to maintain a parallel alignment to the drum. Most modern thickness planers use a 4 post design. Are there any easier to construct designs? What considerations do you need to have to prevent binding?