Sunday, August 05, 2007
Trying out gearmotors
For now the tiny GM-17's are out of the running. I tested them to see if they were able to turn the 1/4-20 inch threaded rod and got them to operate at as little as 1.5v.
As a rule of thumb I've discovered that for running the positioning system you can generally expect that you will achieve about half of the listed free-running rpm for your motor. Free-running rpm for the GM-17 is about 341, which gives me a translation speed of about 6 mm/sec under no load. Practically I get about half of that, which means that I can do a 45 degree diagonal with x and y axes run by GM-17's of about 4 mm/sec. Those I will have to run at 6 volts.
Running at 6 volts will mean that I have to use an adjustable voltage regulator like the LM317. I bought one of those. It's rated at about 1.5+ amps, but dissipates 15 watts, which is just a shade wasteful.
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