Only one axis moves in negative z directions

Hey all,

I am currently building a Delta machine (very similar to the Anycubic Kossel) for a uni project. I have flashed the Arduino Mega + RAMPS 1.4 with Marlin 2.0.x and have configured the Configurations.h file. Everything is working just fine, x, y and positive z moves work perfectly.
But: When it is supposed to make negative z moves (say from Z210 zo Z200), only one axis(X) actually moves, when all three should actually move at the same time.
Same happens when homing. Everything works perfectly, all axes home properly, but on the last step, when it moves down a little bit to get away from the endstops, two axes just dont move.
I would be surprised if it was the hardware, since all motors can move in all directions (as observed whilst homing and X + Y moves).

Am I overlooking some weird setting in Marlin? Do you have any general tips or thoughts? Any help would appreciated very much!

Niklas

Are you able to share your Marlin config?

Yeah, sure!

I have an Anycubic Kossel Linear Plus, nothing jumps out at me from this config as being wrong. Some things to think about though:
1) You said you are using an Arduino MEGA + RAMPS yet MOTHERBOARD is defined to BOARD_TRIGORILLA_14. Probably fine since I think Trigorilla is based on RAMPS but maybe there are differences.
2) I had to enable ENDSTOP_NOISE_THRESHOLD to prevent noise from erroneously triggering my endstops. Anycubic used 2 wires directly wired to a switch. If yours are the same, maybe that's a factor.

Have you verified all your endstops are functioning properly with M119?
What version of Marlin are you using exactly? I used 2.0.5.3 and did not experience this issue.

Thanks for the answer!

Unfortunately, changing the MOTHERBOARD and the ENDSTOP_NOISE_THRESHOLD didn't change the problem. I am using 2.0.5.3, just like you. The endstops are working perfectly.

I am completely clueless. On all gcode lines all of the axes work together perfectly, just on straight negative z moves two dont work.

The only functional difference I can see between your config and mine is that I disabled DELTA_HOME_TO_SAFE_ZONE which shouldn't make a difference.

Have you tried an older release of Marlin? Since this is an Arduino I'd try 1.1.9
Have you tried swapping around the stepper drivers around?
Swap what connector the motors are connected (and endstops to match) to on the RAMPS?
Do you have another Arduino / RAMPS to try swapping out?

This issue is really weird.
I've tried changing the firmware to M1.1.9 but the exact same behaviour ocurred. This led me to believe that its a hardware issue after all. But I switched the motors around and it is always the same ports that dont work in this peticular situation (Y and Z). So when I switch X and Y around, now the previous Y works, but the previous X doesnt.

Another peticular piece of information I did not think was important: I am using DM420 single axis drivers (similar to TB6600 or TB6560) and just connected the STEP and DIR pins from the RAMPS board to the drivers. Maybe there is some kind of jumper I need to connect or something?

Edited 1 time(s). Last edit at 06/13/2020 04:18PM by NiklasH.

HOORAY! The issue was that the enable port of the DM420 driver was not connected to 5V. Stupid mistake one might think, but still extremely weird because all other moves worked. Well whatever.

Thanks for your help, thehankinator!

Edited 1 time(s). Last edit at 06/13/2020 04:50PM by NiklasH.

I'm glad you got it sorted out!