Self test failure: Y-axis length
I have a pre-assembled MK3 that I received earlier this month. I had been printing on it successfully since then. However, I had a print get interrupted due to a crash (head crash?) a few days ago. Afterwards, when I tried printing I was seeing poor adhesion on the first layer as well as the printer seeming to jump to to a different X,Y position. I decided to retry the self-test and calibration process, i get the the following error:
Selftest error:
Please check:
Axis length
Axis Y
I checked that there was nothing blocking the Y axis motion (zip ties, etc). I don't see any physical endstop switches, and I seem to recall that the MK3 uses a different method for detected endstop.
How can I find out how to fix this? Is there additional information I can provide or other troubleshooting I can do?
Thanks for any pointers.
Lewis
Re: Self test failure: Y-axis length
Hi Lewis.
Both X and Y axis. Use stall current to detect the ends of travel. I suspect you have a cable bundle preventing full traverse or something binding. I would suggest checking the extruder cable bundle is neat and tidy. Then check that rhe axis can travel full distance without excess resistance.
Perhaps wipe the smooth rails clean and oil with light machine oil or 3in1 or sewing machine oil. And run the x carriage back and forth to distribute the oil.
Then try the tests again
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: Self test failure: Y-axis length
Thanks for the pointers. I removed the heated bed so that I could watch the carriage move as it ran the self test. I didn't see any of cables catching or rubbing. However, the Y axis move feels "rougher" than the X-axis (with similar bearings). I lubricated the rods with sewing machine oil but with no improvement in the stalling. I found a mention of lubricating the inside of the bearings on the rods in the manual; I will try that next (after I get over my nervousness of taking apart the printer and possibly making it worse). One thing that is interesting is that I can move along the Y axis using the control panel knob millimeter by millimeter without the stalling kicking in until I hit the ends of the rods (as expected); does it have a different stall limit? I guess it's time to read some C code....
Thanks again.
Lewis
Re: Self test failure: Y-axis length
Sorry to bump this thread, but were you able to find a solution to this, Lewis? I ended up running into the same issue all of a sudden with my pre-assembled MK3, and the symptoms sound exactly the same with mine (rough Y movement with steppers disabled, self-test fails, but I can move the Y axis across the entire length using Settings > Move Axis). There isn't anything blocking bed movement in my case, either.
I'm not opposed to a partial teardown (I used to have a Wanhao Duplicator i3 clone so I'm used to taking printers apart :P) but I'd rather avoid that if at all possible.
Thanks!
Re: Self test failure: Y-axis length
I have exactly the same issue and tried all proposed solutions with no hope. 😐
Re: Self test failure: Y-axis length
The issue with mine was that one of the bearing seized (and ultimately gouged the rod). Make sure that they're smooth (you can see imperfections pretty easily, as the lubricant will tend to gather in the ruts) and that you can smoothly move the bed back and forth by hand from one end to the other when the steppers are disabled.
If the y-axis binds up when you try to move it by hand or if you notice imperfections in the rods you'll have to contact support for new parts.
Re: Self test failure: Y-axis length
I am having a similar problem. During the "Wizard" I get an error on the Y axis length. It also sounds horrible. The movement of the bed is not nearly as smooth as the movement of the x-axis. I've tried loosening the nuts on the u-bolts holding the linear bearings, removing and re-tensioning the belt, re-centering the belt. I believe the firmware is 3.2.13. I could use some more suggestions. My next desperate attempt might involve rebuilding the whole y-axis.
Re: Self test failure: Y-axis length
It also sounds horrible
Have you checked that the bearings were at the right angle when you installed them? https://manual.prusa3d.com/Guide/2.+Y-axis+assembly/507?lang=en step 23. Did you loose any of the bearing balls? Are there any scratches on the rods?
Re: Self test failure: Y-axis length
I did check the angles when I installed them and there were no lost bearings, but I can always check again. I'll inspect the rods for scratches, too. Thanks.
Re: Self test failure: Y-axis length
Taking apart and reassembling the Y-axis fixed the problem. When I did so, I marked the linear bearings with a marker on the outside to show where the bearings were so it was easier to line them up in assembly.
Re: Self test failure: Y-axis length
Hey just had that issue on the first test and solved it by tensing the belt in the Y axis. Hope it helps!
Re: Self test failure: Y-axis length
Hi all,
I have experienced the same self-test failed result pointing out that I should check Y-axis length today. Before I ran the self-test again, I used a few minutes while cooling the hotend to google this thread and now I want to add my solution along with thanks to all who helped here.
Fortunately, my fix was pretty easy - I noticed that Y-axis motor turned for a while after the bed reached the end of its path. The problem was a loose screw in the gear on the motor axle... I have no idea how could it get loose (I tightened it myself because the printer came as a kit, but it somehow managed to get loose), but it was enough to tighten both screws, reposition the belt and voila, the printer is running flawlessly again! 🙂
Thanks to all, who invested their time and knowledge in replies!
Have a nice printing! 🙂
Re: Self test failure: Y-axis length
Hi all,
I have experienced the same self-test failed result pointing out that I should check Y-axis length today. Before I ran the self-test again, I used a few minutes while cooling the hotend to google this thread and now I want to add my solution along with thanks to all who helped here.
Fortunately, my fix was pretty easy - I noticed that Y-axis motor turned for a while after the bed reached the end of its path. The problem was a loose screw in the gear on the motor axle... I have no idea how could it get loose (I tightened it myself because the printer came as a kit, but it somehow managed to get loose), but it was enough to tighten both screws, reposition the belt and voila, the printer is running flawlessly again! 🙂
Thanks to all, who invested their time and knowledge in replies!
Have a nice printing! 🙂
Get some Blue Locktite NOT RED) and use it on grub screws; you can easily strip the hex socket in them if over tightened and if not tight enough the vibration will shake them loose so Locktite for the win for this problem