Back during the low times of 2020 I picked up a half-finished Clausing 5937 CNC lathe conversion. Now that it's come up to temperature in my garage for the past year and a half, I figured it's about time to finish it and start making some parts.
The problem I'm facing right now is while I got servos, ballscrews, and a power supply with the project, I didn't get any drives or control electronics.
I'm planning to run linuxcnc as my controller, and I believe a Mesa 7i97 will provide all the I/O I need with encoders connected directly to the mesa cards and the analog out connected to the yet-to-be-selected servo drives.
Motors I have are Electrocraft brushed DC motors P/N 643-003-0132, and 0644-06-011. I can find some old docs referencing these P/Ns directly, but only a peak current is provided, no continuous.
Electrocraft has some legacy documentation for motor parts 643 and 644 (assuming these might be updated versions of the same models?) with similar specs and a continuous current rating is provided, though there are 3 ratings provided for each motor and I can't find an explanation of why.
I've attached PDF files of the two docs that I found in case some other unfortunate soul finds themselves searching these part numbers so they don't have to go through what I have.
Based on this info, I think my current ratings are 40/7.7 for the 643, and 24/4.8 for the 644 (which seems odd since it's bigger but I'll roll with it for now)
Now the crux of the issue is this: how do I size a servo drive for these, assuming the motors are correctly sized for my machine? Should I aim to have enough current to max out the motors? Or should I try to undershoot so that I don't risk overcurrent from bonehead mistakes? Do I even need a servo drive if I'm only using it in current mode?