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Self test failure: Y-axis length  

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ryan.c46
(@ryan-c46)
New Member
Self test failure: Y-axis length

Hey guys! I'll try to get a video uploaded soon (currently in a work meeting), but I'm having an issue with the self test. When it gets to the Y-axis test, the heatbed moves smoothly along the axis, but then it gets to the end of the rods and the motor keeps trying to pull it back, even though there isn't any more track. Then it runs to the front and does the same, and then goes to the back.

Each time it hits the front and back I can hear the motor straining and grinding as it tries to keep the bed moving.

I've seen other people say that the rods might need to be oiled, but I don't know if that's the case here.

Any advice would be appreciated!

Posted : 26/01/2019 2:08 am
Mustrum Ridcully
(@mustrum-ridcully-2)
Honorable Member
Re: Self test failure: Y-axis length

running the motion in all directions to stepper motor stall is what the electronics in the MK3 uses as its end stops so a certain amount of this is expected and normal.

What do your gcode prints (on your sd card they are presliced to run well on a mk3) look like when you print them?

use the methods in this thread to set your live Z
https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html

Posted : 26/01/2019 2:18 am
ryan.c46
(@ryan-c46)
New Member
Topic starter answered:
Re: Self test failure: Y-axis length

Not sure if this helps at all, Randolph, but here's a video of what's happening.

The grinding sound is pretty loud along the Y-axis. Heatbed is off so I could get a good look at the rods while the test was running, but the issue was happening while it was on, too.

Posted : 26/01/2019 3:13 am
Bunny Science
(@bunny-science)
Noble Member
Re: Self test failure: Y-axis length

When it is making the grinding noise, is the Y-motor halted, missing steps (as it should) or is it continuing to spin and jump the belt teeth?
If the latter, it's too loose belt tension. I can't tell from video what the motor and pulley are doing during the noise. You do nicely show that the carriage is moving full range.

Posted : 26/01/2019 3:54 am
ryan.c46
(@ryan-c46)
New Member
Topic starter answered:
Re: Self test failure: Y-axis length

So, I did what guy suggested and tightened up the belt for the Y axis, but I then kept getting an error on the X axis saying that the pulley motor was loose. After looking around I saw a few solutions where people tightened various screws. I attempted to tighten the screw above the X axis motor and the 3d printed part cracked. My question is, can this be fixed with glue?

Posted : 26/01/2019 5:11 pm
Robin
(@robin-4)
Estimable Member
Re: Self test failure: Y-axis length

Dont be too concerned about that. just 2 part epoxy glue it as best you can. Then re-print a new one when you can. It will hold on just the 2 screws if needed.
Its a poor design belt tensioner, there are better ones available now to print.

Posted : 26/01/2019 6:07 pm
Bunny Science
(@bunny-science)
Noble Member
Re: Self test failure: Y-axis length

Ouch!

For broken PETG parts, you can also "weld" it back together with a temperature controlled soldering iron and PETG filament.
The welds end up stronger than epoxy will hold PETG.

I agree, the stock x-axis tensioner design is poor. That's a big reason I switched to a Bear x-axis and extruder. Much finer and larger range adjustment and you can move the x-belt tooth position without taking the entire extruder cable assembly apart, but we're getting off topic.

Was the y-axis jumping teeth during the buzzing noises?

Posted : 26/01/2019 6:47 pm
Mustrum Ridcully
(@mustrum-ridcully-2)
Honorable Member
Re: Self test failure: Y-axis length

as guy said it was a slipping belt on the Y as for the cracked x mount Mine did the same and I use super glue and a toolmakers clamp and printed a replacement then tensioned X by manual twisting the stepper and doing the screws up tightly then I took the clamp off and just decided to run it until it broke again but the glue repair has held for several months...

Posted : 26/01/2019 8:17 pm
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