8825 driver not working correctly

I have 8825 in cnc shield and they make my nema 23 motors run spuratic. I switched with 4988 and work smooth. Why is this happening and will these 4988s handle nema 23 2.12a motors? Why wont the 8825s work, i have adjusted the vref up and down and still eratic?

Hello.

There are differences between the DRV8825 and the A4988 stepper motor drivers, and depending on your setup those differences might affect the performance. You can find a section on the product page called “Key differences between the DRV8825 and A4988” where you can check the difference against your setup to see if that might be causing problems.

It sounds like you are trying to set the current limit by turning the potentiometer without reading VREF. That is not an appropriate method for setting it. You should follow the instructions in the “Current Limiting” section on the product page instead. Also, since your stepper motors current rating is 2.12A, I recommend setting the current limit to the max continuous current limit of the driver to avoid damaging the driver.

If those do not help you solve the issue, could you tell me what you are using to supply power to the stepper motor and provide a link to the motor’s datasheet?

Grant

Thanks Grant for the quick response. Now I have another problem! Motors
running great on bench (4988 drivers) but when I bolt it to the machine it
runs erratic.

Could you describe the erratic behavior you are seeing in more detail? What changed between your bench setup and when you put it into your machine? Did the bench setup have the same load as the machine setup? Could you post pictures of your setup that show all the connections you have?

Grant

Thanks Grant, the erratic behavior - give code and makes a couple
revolutions and hums for a bit then another revolution then stops.
The only thing that changed between bench and machine is length of wire.
18 awg, longest run being about 10 ft. (5 x 5 plasma) No load on each
setup. Motors will only run on green 4988 (any vref) or purple 8825 drivers
(.60 vref only) Arduino Uno, cnc shield, nema 23 (attached photo, bipolar
serial ) 36 v power supply set at 30 v, grbl, universal g - code sender,
easel. Motor runs fine until I bolt it down. Questioned a ground problem,
but when set motor in position, not bolted, works fine. As soon as I
tighten bolts fouls up. Should I use shield wire? And whats with the
drivers, shouldn’t the purple drivers 8825 be set higher vref? Thank for
any input

Nema 23

Hello.

You should be able to set the DRV8825 to 1.5A (a VREF of 0.75V). Could you post pictures that show your setup and some pictures that show how everything is connected?

Grant