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Stepper compatibility with RAMPS 1.4 board and A4988 Drivers

Posted by asdasd123 
Stepper compatibility with RAMPS 1.4 board and A4988 Drivers
September 18, 2017 07:16AM
Hi all,

This is a quick question that I can't seem to find the answer of on the wiki as I'm having a bit of difficulty finding out the max current stepper motors that can I could safely run on a RAMPS 1.4 board.

All I seem to be able to find is that "It's fine with NEMA 17, but not 23's". But I've found Nema 17s with current rating's all the way from 0.4a up to 2a confused smiley

I happen to have some of these already, that I'd like to be able to use if possible : Hictop 1.5a Steppers

Could someone more knowledgeable than me please let me know if these steppers would be ok with the ramps board and some A4988 (I'm guessing the ones I have are the Chinese knockoffs).

I'm planning on having a dual Z setup + 1 X + 1 Y + 1 extruder (5 in total)

I think I heard that the max current was 5A through the board, and I'm wondering if 5 of these motors are likely to draw that in one go.

Many thanks

Jack
VDX
Re: Stepper compatibility with RAMPS 1.4 board and A4988 Drivers
September 18, 2017 07:41AM
... your motors should be OK - I'm running some machines with NEMA-23 stepper rated for max 1.75Amps, which are "happy" with RAPS128 drivers set for 1.3Amps.

In "normal" use you'll run max. three motors simultanuous, but the averaged current will be lower than the sum of the three settings, as it's pulsed current, not CW.

The "max. 5Amps" could be a roughly estimated value for the max. load per track or connection pin - this is mostly too high for the cheapish boards and plugs, so better avoid this high loads ...


Viktor
Re: Stepper compatibility with RAMPS 1.4 board and A4988 Drivers
September 18, 2017 08:17AM
In that case, I'll try them out and trim the pot's on the A4988 to the lowest that they'll run on with plenty of cooling.

I think I'll go with a lower rated pancake stepper for the extruder to reduce current (it's geared and direct drive so should be ok), as well as maybe drop to two lower rated steppers for the z-axis. I think two of the 1.5a might be a bit overkill for a CoreXY anyway.

I'll add them one at a time anyway and measure the current from the PSU. Fingers crossed!!

Thanks for the input Viktor.
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