Can only move one axis without disabling steppers in between

Just finished assembling my Primo and am working on getting the electronics squared away.

I’m using an MKS GEN L V1.0 with Marlin 2.0 firmware and purchased the stepper wiring harness from the V1 shop, so motors are wired in series.

When using Repetier Host (also tried other control software - same issue), I’m able to initially move one axis as much as I want, back and forth, without problems after connecting. It doesn’t matter which axis I move, it works and moves in the correct direction. However, when I move one axis, then try to move another axis after, the machine doesn’t move and the motors start making a ticking sound. I then have to disconnect the USB cable to make it stop.

While trying everything I could think of, I found that if I turn off the motors (by clicking the button on the control tab in repetier host) before trying to move a different axis, everything moves as it should with no issues.

I’m pretty new to this and have exhausted all troubleshooting I can think of. Any ideas on how to get to the bottom of this? Wasn’t able to figure out how to upload a video, but if that would help, let me know.

Thanks for looking!

I’ll take a shot at it:

Do you have an LCD controller on the unit and does it work using that (Eliminate Repetier Host, USB Cable, etc.)

Do you have enough power 6amp+ power supply? (It’s possible you are running out of power when powering up the second set of steppers)

Have you tuned the controllers to the right Vref (Again drawing too much power to one and not enough to others.

Can you disconnect the steppers for one axis and try again, if that doesn’t work disconnect the next set and retry. Maybe something is shorting between 2 steppers and occurs when the second set is activated.

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This is a strange problem that I have no idea about, but I have a troubleshooting step. Steppers engage the first time they are moved. So move one axis just a bit, then verify that both motors on that axis are engaged, and that the other axis can still be freely moved by hand. Repeat with the other axis.

Also your behavior might be what would happen if you configured your firmware for CoreXY instead of a regular rectangular setup.

Yeah. I suspect power supply. I also wonder if the driver current is set in the right ball park.

Thank you all for the great ideas! I really appreciate the help!

I ordered one of the “discount smart controllers” and it gets here tomorrow, so that will be the first thing I try assuming I don’t get it resolved with all of these great suggestions.

The power supply is the one from the V1 shop, so I assumed it to be good, but I’ll measure the amperage and ensure it’s outputting what it’s supposed to be.

This is something I thought to try, but I was afraid of frying stuff, so I shied away from it. I wasn’t sure what the “right vref” was either, so I figured I’d ask before messing with the pots on the stepper drivers. I just read up on it and it seems pretty easy, so I’ll give it a try.

This is an excellent suggestion and I will try it and report back.

Also a great suggestion that I hadn’t thought of. Will give it a try and report back.

I wasn’t even sure what CoreXY was until I googled it, but I doubt this is the case. I downloaded “preconfigured” firmware from V1’s github and only changed the Motherboard definition in the configuration.h file. Is there a specific section of the firmware I should look at to ensure this is (not) set correctly?

It is probably fine then. They usually fail broken, not limping along. You won’t be able to get a sense of the max current by measuring the current. If you measure the voltage, that will tell you more. If you have a 12V, 1A powers supply and you connect a 12V 2A load, the symptom will probably be a power supply that only produces 9V, or 5V or something, or maybe some smoke. If the voltage is above 11V with both axis engaged, then the psu is fine.

As a crude rule of thumb, start with 0.7V from the potentiometer to ground. It is useful to use a tiny flathead screwdriver and keep the multimeter attached all the time. Put the black on the ground screw of the incoming power and the red on the screwdriver.

My guess is, this is the problem. These have to be adjusted to reasonable settings or they will be way too low (causing skipped steps, a crunching noise) or way too high (which would lead to a lot of heat).

This was the issue. I did some research, then the math, and vref should be somewhere around 0.8, so I went with 0.75 to be safe (they were at about 1.5 out of the box). I can now move all axes without “disabling steppers” in between!

I can’t thank you all enough. It’s truly awesome that you take the time our of your day to help others. Once I learn a bit more, I’ll be inclined to do the same.


Glad we were able to help… we’ve all made the same mistakes and gotten help here so it’s nice to repay the community.

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