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large x axis layer shift (>2 inches)  

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chris.y7
(@chris-y7)
Active Member
large x axis layer shift (>2 inches)

HI everyone,

I'm new here, new to 3d printing and new to my Prusa mk3. I assembled the kit and found the construction very easy. Initially I made a couple of prints that were perfect. The Prusa logo and the planetary gear bearing. Both printed really well and I've not seen one of these bearings that spins better than the one I printed.

But I have started experiencing failed prints because for no apparent reason the print head just lifts , it moves to the front of the bed and then returns to a printing position but it is more than two inches to the right of where it should be. When I stop the print and then home the head, the head returns to a place almost midway at the front of the bed. The only way I can get home re-calibrated is to run the self test again which always shows that everything tests ok. I have run the calibration wizard so many times now I can't count and everything always calibrates without errors. But the next time I try to run a print, soon after it starts it does this x axis shift. After I can check the failure stats and I see an x axis crash. I can't see any problems with anything being obstructed. I was able to catch the problem on video while trying to print the Prusa logo again. Here it is...

https://1drv.ms/v/s!ApEIZVkQ_KsXq2ktGxSDvkFnZhRw

This clearly shows the issue. I've chatted with support but they haven't been too much help. I was asked to update firmware which I did even though my printer came with the latest 3.1.3. Updating didn't help but I didn't expect it would. I've been pointed to the article on Prusa's site about layer shifting but I just don't see an issue with anything. Any ideas would be greatly welcomed. BTW I'm trying another print right now with crash detection turned OFF. Has anyone had problems with crash detection?

Thanks for any help you might offer.

Chris
Columbus Ohio

Cheers
Chris

Postato : 04/05/2018 2:03 am
Olef
 Olef
(@olef)
Prominent Member
Re: large x axis layer shift (>2 inches)

From your video it looks like your printer detected a crash, but then for some unknown reason it homed to the wrong place - in the front centre of your bed instead of the front left. From there the print was doomed as it resumed from it's new home position which was a long way from where it should have been.

I suspect binding in your x axis which is fooling the printer to think it has reached X home when it has not. Try unhooking your belt and moving the axis by hand. Solve any rough travel or hesitations. Rods, bearings, cabling.

Has anyone had problems with crash detection? Easier to ask for anyone who hasn't really. It has been steadily improving as firmware advances but still a good fix is to disable it if it causes issue like yours.

HTH

Postato : 04/05/2018 8:44 am
chris.y7
(@chris-y7)
Active Member
Topic starter answered:
Re: large x axis layer shift (>2 inches)

Thanks for the reply Alfred. You are correct that I'm seeing x axis crashes and I believe I did resolve that. The x belt that I received with my kit was sort of deformed. It's not straight. As a result there wasn't a way to align the pulley so that the belt doesn't rub against the side. I think it was rubbing excessively though and I made an adjustment so there is less resistance. In addition I disabled crash detection. I made a print last night which took about 3 hours and it finished perfectly.

Cheers
Chris

Postato : 04/05/2018 2:16 pm
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