Topic 1:
I think I figured it out! I've been obsessing over how to make sure that the electro-mechanical portion of the CNC router would be compatible. But, given the odd and random collection of parts that I've seen on this site, I couldn't figure out how to make a common interface that would control them all.
I think I've got it! You don't even try to make it "compatible."
You install a "driver" or some sort of a layer between the g-code interpreter, and the parallel port. It's calibrated to your actual equipment...probably number of steps per revolution, or some similar unit that would be common to all drive systems.
Then, you let the computer determine that to move 5 units, you send "so" many pulses to the controller module.
Is this how it actually works? It is a workable solution.
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Topic 2:
Motor specifications. Like I said, I've seen "random parts" mentioned on this forum, which leads me to believe that almost anything can work. But, if starting with a clean sheet of paper, what type of specs would be good for the stepper motors?
Is something like this good?
http://www.bgmicro.com/prodinfo.asp?...tepper&stype=3
48 steps per revolution, 1800g.cm. holding torque. The resolution seems rather low, but if it's driving a screw drive this may not be the case. The price is definitely right. And, is 1800g.cm. a high enough torque?
http://www.bgmicro.com/prodinfo.asp?...tepper&stype=3
This one has 1/3 the torque, but 100 steps per revolution, and it's bipolar. Would this be a better choice?
I'm literally trying to learn the basics, at this point. Building a stepper motor controller is not outside of my abilities -- my concern was with the software interface, and if my guess (above) is right, then I needn't be concerned any more.
Thanks!
-- Chuck Knight