Thanks Token, that was a good start for my four day bender of reading about motors, motor controllers, sprockets, chains, gear ratios, machining shaft keys, and etcâ€¦ And combining all of that into a huge spreadsheet to find The Motor. There are a lot of very nice motors out there with some kind of odd-ball shaft that I can't find sprockets for. Or motors that were perfect except for being 12" long when I have 6" of space, so I wasted a day trying to figure out how to make a 90 degree angle transmission, or find one for less than $100 (that didn't happen).
The good news is that when I got sick of that I could go out to the garage and weld. Welding is so relaxing, if I ever make something again I want it to involve more welding and less thinking. I am just starting to get that 'stack of dimes' look that people think is pretty, and the inside corner penetration is much better than it was in the past. I am starting to really like aluminum.
And, after all that learning and reading, the current plan is now:
Motor: Ampflow E-150, 0.5hp 4700 RPM, 2.2 pound/foot torque motor ($79, but has a bigger brother that will fit in the same bracket for $299 that is 5x more powerful, in case it doesn't work)
Motor Sprocket: 9 tooth, 1.3" diameter, #35 chain
Crankshaft Sprocket: 114 tooth, 13.8" diameter
Gear ratio: 12.6:1
Torque at crankshaft: 28 foot-pounds ("big brother" would be ~130 foot-pounds)
Motor RPM at 4mph: 2200
Chain speed at 4mph: 700 FPM (within the 600-800 guideline)
Center distance between sprockets: 13", chain length: 53" (within the 30-50 times pitch length guideline)
Wrap of chain around small sprocket: 122 degrees (120 is the minimum)
Motor Controller: Roboteq AX2550 80amp continuous dual channel motor controller
Remote Control: Spektrum DX3E 3 channel RC car controller
Success will be if the machine crawls forward at 1/2 mph. The 4mph target would be icing. I just don't want the machine to need a push start or to not budge an inch while the motors hum.
The metal supplier doesn't cut perforated aluminum. Does it mess up their shears? So I am thinking of using electric shears from Harbor Freight, the kind that look like an electric drill with snips on the front:
http://www.harborfreight.com/14-gauge-s ... 92115.html
I've never used those things before, but saw a Youtube video of them cutting and think they might work well going through all the holes. Do you think it will work? I am thinking of those things over a circular saw because I am out of room in the garage, and that looks like something I can lay a 4x12' long sheet on the grass in the yard and cut up without making a huge mess.
And now I am looking at trailers. I want to find one in the next two weeks, so that I can bring this machine to my collaborators house in Los Angeles. He is helping me with the electrical parts of this machine, and I have a mean plan to park this thing in his driveway for two weeks while my wife and I head out of the country for a wedding. This has become another huge page in a spreadsheet, since the machine is 62x96x92", which is a pretty wide to get through an enclosed trailer's door, even if I put it through sideways. So we are looking at making the legs fold in somehow for transport, so that the machine is 73" long instead, to fit sideways in a 7' wide trailer, as long as the door is wide enoughâ€¦ If I can't figure this out I am half tempted to just go with a small flat bed trailer, though then this thing will sit outside under a tarp for 11 months of the year on my friends farm, instead of completely inside a little trailer. The 8' wide trailers look like they might be harder to drive, and mostly come in very long sizes (14' and above). I've never towed a trailer, but the 7'x12' trailers I've seen in the neighborhood seem more human sized than an 8x14 or 8x16. Do you guys think there is much of a difference in handling the larger trailers?
My bicycle chain is horribly rusted from the Playa. On McMaster I see chain that is 'Corrosion Resistant Treated Carbon Steel' -- is that good enough or should I look at going up to stainless steel chain?