Axis Z Ramps 1.4

Hello, help please with config of Axis Z driver on Ramps 1.4. There are two stepper motors Nema 17 1.7 A connected to one driver.How to set Vref on A4988 to control both of engines, or I need to set one one 5th driver to control second engine?

steppers are in parallel so you double the vref... but that exceeds the A4988 max current rating....

So try 1.7A and cross your fingers it is enough current. (it is on most I3 type machines, but depends on how heavy your X axis is)

If that doesn't work you can try rewiring the steppers in series, or use E1 as a second Z

NB vref sets the maximum current, which is not necessarily the best or required current. It is however the loudest

One engine will be 28byj 12V and four Nema 17 1.7 A
Maybe install 5th driver better?

28byj will be on extruder

I'd just experiment with it, set the current to the lowest setting then keep bumping it up until it runs smoothly without skipping steps. Create some gcode that runs the z axis up and down at the maximum velocity and reversing instantly (which tests acceleration/deceleration). There's a balance between noise and smoothness too. If you can't find a setting that's to your liking you can look into a separate drivers for Z axis. I've always used one stepper motor and used a timing belt to drive both lead screws at the same time. I had a 970mm belt. I use it now on my new corexy printer with an even longer belt (1150mm iirc). If you use M5 leadscrews a single stepper motor may not be strong enough.

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Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]