stepper question

[norm535]

on a long x axis with twin rack and pinion gears using two steppers, do you require two driver boards or can two motors be used in one driver board.

Thanks from Norm

[jschmitt]

I would use 2 drives because I don't think you can control current to the motors decently with one drive. Depending on size of motors, and if the motors were wired in parallel, or in series to each other, you would need either a high current driver, or very high voltage driver, or both, to make the thing run decent.

Here is a post the subject about a guy who tried it with sucess:
http://www.cnczone.com/forums/showthread.php?t=87407

[RGeo]

If it is at all possible to run one shaft to both pinions and use one motor. Perhaps it is physically impossible to do this, if that’s the case then excuse my post. If not, read on: A stepper, being open loop can easily get out of step with the other motor. This is still possible; although, less likely if you are running at low speeds with little or no load, as in a printer or a flame cutter, i.e. not tool load. However, if you are operating a router, lathe, mill, i.e. something with tool load, I think you’re asking for trouble when blind syncing steppers. This would give a whole new meaning to the word “rack”, as in all racked up. Opt for one motor and a common shaft, if at all possible.

[norm535]

thank you guys I was not sure if it was essential or a waste of money to use an extra driver board. better to be safe rather than sorry. so will go with 2 drivers now just need to decide which ones..... Huum let me think

Norm