RUMBA: stepper (&power) selection
February 08, 2018 06:13AM
Hi all,
I'm new to this forum, and quite new to automating machine projects smiling smiley

I am making a vertical drawing robot, much like Hektor / Makelangelo / OpenWall etc. For this I got a RUMBA board (+ DRV8825) as it seems the most reliable all-in-one board (and I'm looking to upscale the V-plotter).
My local electronics shop sells 2 kinds of stepper motors that could be fine for me:
- a lightweight 24V / 600mA stepper
- a NEMA17 12V / 350mA stepper

As the motors will be on board, the light 24V stepper is more appealing to me, along with its higher max. power and more favourable characteristics (less gearing needed). But does it require a 24V power supply on the RUMBA board as well, or is there some internal transfo? The information for the RUMBA board says it can power anything between 12-35V. But how do you set the voltage for the motors? Does the power supply have to match this exactly? Any other considerations when using a different voltage than the 'standard' 12V?

I have a 12V power supply ready to use and could probably go with the 12V stepper for now. But I'd really like to understand how it all works together on the board and drivers. So if you know a good information source, please kindly point me in the right direction.

Thanks!
VDX
Re: RUMBA: stepper (&power) selection
February 08, 2018 06:28AM
... steppers with "12V" or "24V" are pretty oldstyle types, some of them even unipolar, so not suited for the actual bipolar drivers - better search some with higher rated currents around 1.2 to 1.7A, what's the better parameter to look on ...

The motors have then something like "3V", what's not a problem, as the drivers controls the current through the windings and the voltage "follows" then Ohms law.

If the motors are powered with 12V or 24V only defines your max. speed - with 24V the maximum acceleration and pulse rate (or speed) is slighty faster than with 12V ...


Viktor
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