Adjusting DVR8825 Vref

[midiman310]

Seen a lot of posts regarding stepper motor issues. I have the DRV8825 Pololu Stepper Drivers and 42BYGHW8111Stepper Motors which come with my Acryllic I3. Initially I did not bother to adjust the drivers out of the box and printed using as is. However, one day I touched my X axis motor housing one day while it was in the middle of the print and noticed it was scorching hot! Same with the Y motor. Decided to check Vref and it was cranked up to 2 volts. Turned it down to .8 volts and it runs quiet, gets very warm but not hot. Figured it would help to make the motors last a lot longer. Vref on the Z-axis was 1.8V but decided to leave it there as the driver is supplying current to 2 motors anyway. Here's a quick pic of where to probe when adjusting the DRV8825.

IMG_3827.jpg (107.56 KiB) Viewed 33325 times

Probe right on the screw. Black meter cable is attached to ground.

[XYZM]

Hi

Can you explain where you connected the ground??

Can I connect the ground to the outer case of the USB port?

I think thats a ground..

[midiman310]

The ground was attached to one of the available screws to my power supply (there were 3 screw points on it) just wanted it out of the way and did not want to hold the ground probe. It should be all right to connect to the outer case of the USB port. I do believe they share a common ground with the RAMPS board and drivers as well.

[Aeonster]

Hi,

There is actually a pretty good youtube video about how to adjust the current for drv8825 drivers.
https://www.youtube.com/watch?v=89BHS9hfSUk

They go slowly step by step, I like that