I'm stumped: Self Test Error: Axis Length: X Axis.
Hello! I wasn’t sure where to post this, and I apologize for being rather green with this whole 3D printing thing. I assembled my printer from the kit, I had a few screws loose, but a very pleasant Prusa centric Discord group helped me narrow down how to fix that, and I was golden for a while. I’ve only had my printer a few weeks. I have much to learn but I’ve been content with my prints.
Everything was fine until yesterday. I tried to change filament colors and ended up having to replace my PTFE tube. I used the online tutorial for that and I believe I did it correctly. At the very least I was able to replace the PTFE tube successfully then switch out the filament normally. I thought it would be wise to run a self test to make sure everything was fine. It checks the fans, raises the extruder assembly an inch or two then stops and produces this error:
Selftest error!
Please check:
Axis length
Axis X
When I click the knob to move on from the error screen the extruder assembly will move slightly to the right.
I’ve stumped the discord group. We did some trouble shooting and they couldn’t help me. I looked up some forums with similar issues, tried a few things like tightening screws, loosening screws, etc… and I’m not getting anywhere. I’m concerned I did something wrong when I replaced the PTFE tube. I don’t really wanna be “that person” who only enters a discord chat for help, as that can be tiresome.
Their suggestion was to ignore the self test and try to print something. I did that, and she prints well enough. I don’t hear any strange, unsettling noises (although I’m not 100% sure what it’s supposed to sound like.) but I don’t really like not being able to pass the self test.
I have my printer up to date with the firmware, flashed it on the 20th of sept.
So, my questions are:
Has anyone else experienced this?
Does anyone have any ideas where I can go back and make sure nothing is stuck, too tight, too loose, ect?
Would it be worth dismantling certain parts and putting them back together?
Should I keep ignoring the failed self check?
Do you need more information?
Thank you so much for any help, I apologize about the long post.
-Judi
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
No idea what you have tried, but power off.
Move the extruder from one side to the other and back.
Is the motion smooth, or do you feel any binding?
The MK3S has no endstops. It determines end of travel by motion resistance. Binding in the middle throws everything off.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
I’m not 100% sure what it’s supposed to feel like. I made a video.
it feels smooth, I’m not exerting much force to move it. But, as I said, I’m not sure what it should feel like.
If there is too much resistance, where could I go make adjustments?
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Hi Judi,
When you changed the PTFE, did you remove the Zip ties which restrain the extruder cable bundle behind the extruder?
if you did, you may have replaced them slightly wrong, causing them (Wire bundle, sheath or Zip Ties to touch the main frame.
you will have removed the front and left hand fans... did you make sure the fan cables are properly tucked away? and that the Pinda cable is in the correct location?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
@joantabb
thank you for the reply. No, I didn’t remove the zip ties holding the cable bundle behind the extruder. I did my best to be careful with the wires. I’ve provided some photos, maybe they can illustrate an armature builder error I’m clueless about.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Hi Judi,
Looking at your video, it looks as if the end of the heatbed cable braid, is not trapped inside the heatbed cable clamp. this is likely to lead to early failure of the heatbed cables,
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Is the noctua fan (on the left) seated fully at its rear? Check if it is sticking out due to the fan and motor cables that run behind its upper edge. If it is sticking out, the fan or its mounting screws may limit x-motion.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
I think Joan found it: the heater cable is well outside the rat tail support and will prevent proper X-Axis homing. While fixing that, you can also fix the fabric overhang that also can limit movement. The lower cable tie ends we can't see are also suspect, they must be positioned on the underside of the support.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
I’ll do my best to take clearer photos. I’ve secured the heat bed cable with its nylon fabric casing in it’s appropriate spot.
I re-did the cable management coming from the back of the extruder according to the instructions in the manual. I cannot figure out how to push the thick red wires coming from the hot-end any further in.
If someone has a visual reference of how it should look, or a tutorial that’s not in the assembly kit booklet, I wouldn’t mind looking at it.
Please let let me know if you need more photos.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Apparently the solution was to try the self test, unsuccessfully, a few more times, hit the "auto home" thing, then try the self test once more... she finished the self test successfully with no problems. No idea what I did that helped.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Hi Judith,
the |Heatbed cable sheath looks much better,
the Hot End red cables look very much like mine, so no worry there.
it's good to hear that you have resolved the error report,
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
It probably was your doing an auto-home that let the printer avoid the error. It's not a common occurrence, but I've seen it during testing of 0.9 degree motors. The x-axis failure would begin with the axis trying to move left, but not actually moving because it was already at max left travel. When you auto-home, carriage is left slightly further right. This gives the initial move command space to move the carriage a little before hitting the stop. I believe the initial leftward motion requires some distance to build up enough velocity to register a hit. If it is already all the way left, it doesn't get a chance to do so.
Auto-home succeeds because it begins by moving the carriage away from the end stop. This gives it some running space before the initial hit. Hence, it is able to work. Apparently, the self-test startup does not have that initial "away" move. So it can fail if carriage is already max left when you start a self-test.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Most likely pushing on the red wires moved them just enough ... the cables must NOT touch the frame or Einsy. Even my 'loose' textured sleeve has caused me grief that way.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
I was receiving the same error upon running the wizard after flashing the latest firmware. After reading this thread I checked for wiring issues but everything looked good, so I tried an auto-home and the issue was resolved on the next attempt to run the wizard.
I'm not sure the theory about auto-homing positioning the carriage to the right of the axis end is the correct explanation though; I had already tried moving the carriage to the middle of the X axis before the self-test but was still getting the error despite there being plenty of room for it to move before hitting the end of the axis. Since the only change since I had last successfully calibrated and printed was the firmware I'm inclined to suspect there's some software bug here.
Whatever the cause, I can confirm that running an auto-home seems to be the simple fix for the problem.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Also - in that video - the X axis was NOT moving smoothly: the jerky motion is a perfect example of a sticky X Axis.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
@patrick-s50
auto home did not solve it for me,
It seems that it does not even try the x axis test, just immediately fails. on 3.7.2 no problem. and no problem for many months and versions before that.
but calibration goes well, printing also, just the selftest that does not test.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
@tim-m30
I appriciate the feedback. I figured I was not exerting much force with my lady hands to make it move, it may be okay, but I wasn't sure.
How would I go about remidying that?
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
Could you try the following command a few times via a terminal session and report the data returned?
G28 X C
The feedback regarding how the motor is sensing the end stop may be helpful.
=============
You can get a finer feel of how the axis is freely moving by pinching the belt with two fingers and moving the carriage by dragging the belt back and forth. That gives more sensitive touch feedback than pushing the carriage. Catches in movement will be easily felt.
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
@guy-k2
the g28 command does an auto home on x-axis,that works, but with the self test, there is absolutely no x movement at all. Only z goes up and the display then shows an error in x-axis length. (when i look at the x-belt status, it is 0)
RE: I'm stumped: Self Test Error: Axis Length: X Axis.
@gilian-m something deep is messing up. Reading through the firmware self check code, it is really hard to explain how one can get ZERO motion of the x-axis during the self check. You see the z safety rise. The very next thing lcd_selfcheck_axis_sg does is attempt to move the axis leftward to a collision. The motion command is explicit. The failure has to be happening deep in the plan buffer or stepper synchronize routines and those are not easy to screw up with normal code. I suspect some weird setup value is lurking in your EEPROM.
You did perform a factory reset WITH DATA ERASE when going to 3.8.0 right? EEPROM contents for 3.8.0 differ from earlier firmware enough to be essentially incompatible with pre 3.8.0 EEPROM data. One must do a full factory reset with data erase or old EEPROM values will cause all sorts of seemingly illogical failures.