--- On Thu, 7/30/09, Horace Heffner <[email protected]> wrote: > Some of the youtube experiment videos show motors that seem > to run well with low current. I would not have expected the > contact to be so poor. Maybe it *is* indeed poor and > that is key to getting enough torque. The fact > flywheels are required on some experiments is a sign that > contact is poor. Torque is proportional to i^2 in a > good operating range, so putting all the current through one > bearing at a time will maximize torque for the total current > draw.
The one I have runs with two ball bearing race assemblies, has a piece of 5/8" threaded steel shaft through the center, and a ~5" diameter aluminum pulley as a flywheel. You have to turn the thing first before applying current, then it takes off. As far as I can tell, this prevents welding. > Any suggestions for improving steel-steel electrical > contact in the bearings would be appreciated. Not sure how good you want it, exactly. I suppose you could clean the thing in a few solutions to get rid of all the oils/grease in the thing. Maybe stand the entire assembly on its end, remove the top side grease seals from the bearings, and drip in some melted Wood's metal while heating the bearings. You'd have to preheat the bearings before each run, but Wood's metal is cheaper than galinstan. Or buy some real mercury from United Nuclear. But you might not want to go that route. The power supply I used was a 12V 1200 peak ampere car booster pack. Never had problems with bearings attempting to seize. I don't think it is really a problem, especially since things are in motion to start with (the initial spin.) Don't know if I can be of any more help, but if I can, let me know. --Kyle
