New MPCNC build, Y1 Grinding issue first run

Hey Everyone,

I just got done all the hardware and running of wires for my new build which I am extremely excited to share with all of you but first I am having an issue and wanted to make sure I’m not missing something stupid. Anyways I connected my Rambo board for the first time today that I ordered from here to do the initial test run of the build and everything worked except the Y1 motor was grinding back and forth. I posted a short video of it here:

to sum up what I’ve already tried:

-tested continuity from the Y1 motor to the Y1 port ( Results: SAT )

-Switched the Y1 and Y2 connectors on the Rambo board (connected Y2 to Y1 port and Y1 to Y2 port). (Results: Y1 worked correctly and Y2 exhibited the grinding issue)

-switched pin assignments between Y1 and Y2 in Marlin to rule out software. (No change, Y1 continued to grind)

Conclusion: Its not the motor, and it isn’t a loose connection, I have every motor wired up the same in terms of which coils to which pins on the Rambo so I don’t believe its wired incorrectly. It isn’t software based on the Pin assignment change. The only thing I can see it being is that I got a bad board some how. Hopefully that’s not the case and someone can point out something I might of missed. Thank you. Once I figure this out I will be sharing my build with a couple of features that I think people will like…

Thanks again for any help,



Did you get the rambo from here, or amazon?


Also, that looks exactly like what a miswired stepper does. Have you checked to see if the coils are actually on the wire colors you think they are?

I got the Rambo board from here, didn’t want to take any chances of fakes/cheap versions. I checked the coil wiring by checking continuity between wires from the motor to verify my two pairs. also its wired exactly like the other 4 and came in a set of 5. I also tried a different motor and got the same issue using a cable that was verified working on another port.

Interesting. I would say re-flash it just in case I did something funky.

Okay, cool, just checking. We’ve seen some weirdness lately with clones.

I reflashed it a couple times checking and rechecking the firmware but still got the same issue… sadly I think its toast for this project. I just ordered a new one from you yesterday so hopefully I just swap it out and it’s all good.

Let me know if that fixes it, and we can work out the details of the return.

Thanks I will definitely let you know, I wont be able to test it till Tuesday but I’ll let you know as soon as I do! Cant wait to finish this project!

So surprisingly the new board came today before I left so i decided to hook it up and see what happens. I flashed the dual endstop firmware and told it to home and low and behold IT WORKED! Im so pumped that the issue is gone. Now I just need to 3d print a bracket for my router and and then take some beauty photos and Ill share my build. Wont be until mid next week sometime sadly but its coming! Thanks!