X axis shift, 2 times, different print jobs, same part, opposite direction
 
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X axis shift, 2 times, different print jobs, same part, opposite direction  

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SKMoss
(@skmoss)
Active Member
X axis shift, 2 times, different print jobs, same part, opposite direction

hey all.  Interesting issue. I’ve printed the top corners for the prusa lack table enclosure, twice.  Both times, and at the same layer in the print, I’ve had an X Axis shift.  Please note in the picture, the shift in the second (left side) print is opposite the first (right side) print and about 1/2 the amount.  First time the shift looked to be about the distance of one belt tooth, but the second isn’t the same.   

I’m new to this printer, but have printed the rest of the enclosure parts with no issue (several as tall or taller), as well as a few other prints with no issue.

I’ve checked belt tension and it falls within expected limits.  I checked the belt location on the pully and it’s centered (was a little off center for the first print, and adjusted to center before the second)

 

Posted : 15/04/2021 1:28 pm
Dan Rogers
(@dan-rogers)
Noble Member
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

Something may be interfering with your bed movement.  It takes very little force to throw the stepper motor off.  Is your spool binding?  Filament guide catching?  

Did you check that the grub screws on the motor pulley were tightened in the correct order?

Posted : 15/04/2021 2:28 pm
SKMoss
(@skmoss)
Active Member
Topic starter answered:
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

@dan-rogers

Dan, thank you for the reply.  Everything appears to be clear, and unobstructed.  

The part that confuses me, the shift only happens with this specific file, in the same layer of the print.  And I've printed a few other things that have been as tall or taller with no issues.  

It's a 12-hour print. I don't need to do another one at this point, but someday I'll do it again and physically watch the project when it gets to that part of the print and see if the nozzle is catching the part for some reason.

Posted : 15/04/2021 3:07 pm
Dan Rogers
(@dan-rogers)
Noble Member
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

I've ruined prints by touching the bed during a print - it doesn't take much pressure combined with the sudden fast movement of a head.

Anything that is a crash reason would show up in your print log.  Look there to see if the printer detects a crash on that print.

 

Posted : 15/04/2021 6:18 pm
SKMoss
(@skmoss)
Active Member
Topic starter answered:
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

@dan-rogers

Dan, again thanks for the response.

I feel like we’re missing the point.   Nothing is obstructing or bumping the printer during operation.   This shift has happened 2 times.  Same file, same layer in the print, on TWO DIFFERENT prints.  If it was an obstruction you’d expect other prints to be affected.  If it was bumping, it would be a big coincidence for it to happen at the same spot in two separate prints of the same file.

Again, thanks for thinking on this.  I’ll chalk it up to gremlins for now, and if I ever need to print that part again, I’ll monitor to see what happens.

Posted : 16/04/2021 2:18 pm
Dan Rogers
(@dan-rogers)
Noble Member
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

Consider the physical.  For that shift to occur, the belt slipped, or the bed shifted.  Belt slip is usually pulley or belt tension.  I don't see acceleration as an issue if you print these one at a time.

Posted : 16/04/2021 6:01 pm
SKMoss
(@skmoss)
Active Member
Topic starter answered:
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

@dan-rogers

They aren;’t printed one at a time.  The part in the picture is one of 4 on the STL file (Corners from the Prusa Lack Table Enclosure) with 2 the two acrylic panel holder/hinges.   How would acceleration be an issue.

How would the bed shift in the X coordinate?

Posted : 17/04/2021 2:43 am
tdk408
(@tdk408)
Eminent Member
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

@skmoss

My MK3S was shifting layers, and just a dot of lube on my polished rods and the problem disappeared. When is the last time you lubed the rods?

The bearings are made of Delrin, which I consider self-lubricating. They moved easy enough. But still, after a dot of oil no more shifted layers.

Cheers, mate.

Tom

Posted : 18/04/2021 6:07 am
SKMoss
(@skmoss)
Active Member
Topic starter answered:
RE: X axis shift, 2 times, different print jobs, same part, opposite direction

@tdk408

Cheers Tim, thank you for the reply.

 

the machine is about 2 weeks old so the lube was done then.

if the shift was occurring randomly I’d agree  it’s a lube or bump or obstruction.  But both times is the same STL file.  2 prints on 2 different days, in the same layer.

there’s nothing random here.  With the exception of one day it’s shift left and one day it’s shift right.  and one print the shift appears to be 1/2 of a belt tooth on 2 adjacent layers and the second day it was 1/2 half a belt tooth one time.  But again still in the same layers on both prints.

note I’ve printed around 5 stl files that are taller so I don’t think related to where in the z axis the job is.

im at a loss.  But since only 1 file is affected and I don’t need to print it again, I’ll just put this to bed until I get the same issue again.

 

thanks

Steve

 

Posted : 18/04/2021 2:18 pm
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