Strange behavior: X-axis moves randomly back and forth
Dear Forum,
I need your help. I own a MK3S that has worked perfectly so far. I have rarely seen such a perfectly constructed piece of technology.
Since the installation of a Raspberry Pi Zero W (with PrusaPrint) I now have a strange behavior.
When the X-axis moves in one direction (manually as well as via G-code), it seems to move randomly back and forth. And it makes a hell of a noise.
For example, if I go from +0 to +10 step by step, the axis just wobbles back and forth. One step forward, then a few steps back, then another step forward. And so on. Unfortunately there is no pattern recognizable.
The Y-axis and the Z-axis work fine. I disabled the Raspberry (disabled the port in the menu) and shut it down. So it should have no influence anymore. Otherwise I didn't make any mechanical changes, compared to when it was still working fine.
Even a downgrade of the firmware doesn't bring any changes. So it seems to be a mechanical or electrical problem? When I deactivate the motors, I can easily move the extruder, there are no mechanical blockages. The belt is also correctly tensioned, it does not slip over the gears.
Has anyone of you ever observed such a behavior?
RE: Strange behavior: X-axis moves randomly back and forth
A bad motor can cause this. Pull the belt off the motor and see if you can step the motor manually and watch for proper rotation. If the motor is still jumping around, you can check for the connector being inserted firmly at the Einsy, but after that it's probably time for a new motor.
RE: Strange behavior: X-axis moves randomly back and forth
Thanks Tim for the quick answer. I removed the stepper motor - no change in behaviour either.
I just tried the y-stepper on the x-port and behold: same behaviour. So it seems like it is the port on the Einsy that is causing problems.
RE: Strange behavior: X-axis moves randomly back and forth
Try a reset? A PITA to do the calibration but you would zero out everything and and you would get a full self test. Don't know that you would have anything to lose.
RE: Strange behavior: X-axis moves randomly back and forth
If swapping X for Y indicates the problem switches axes, then it does sound like the controller is busted or being negatively affected by the connection to the Raspi ... Have you tried disconnecting all the external stuff and running the MK3 sans cables, etc??
If the problem persists when running naked from the SD card or manually via LCD, it wouldn't be the first piece of electronics damaged by ESD or ground loops.
RE: Strange behavior: X-axis moves randomly back and forth
Late to the show - but I see no indication you tried running without the Pi.
From everything I have read - I would not use a Pi Zero in this application. It is just too underpowered.
I have a Pi 3B with Octoprint already installed - just waiting for my printer.
RE: Strange behavior: X-axis moves randomly back and forth
Late to the show - but I see no indication you tried running without the Pi.
From everything I have read - I would not use a Pi Zero in this application. It is just too underpowered.
I have a Pi 3B with Octoprint already installed - just waiting for my printer.
There have been similar reports for the Pi3 ... the issue is on the Prusa side.
RE: Strange behavior: X-axis moves randomly back and forth
In the meantime I removed the Raspi and reset the printer completely. Unfortunately that didn't change anything.
The way it looks I really damaged my first board in 20 years. 😣
On the positive side: I now have a (nearly working) controller board for my CNC milling machine 😉 . That simplifies the decision there.
RE: Strange behavior: X-axis moves randomly back and forth
For the record: swapped the einsy board. Now everything runs as it is supposed to.
Thanks for your tips!