Urgent: shift on printing

[Nidhal Ben Othmen 0]

Hello,
I faced the problem of shift on layers for the first time while printing a base in the middle of progress. I thought that it may be issued of the configuration of the model on cura so I reconfigure the part but it repeats the shift in the same level of print progress.  Also I checked all the grub screws on belt gears and they seem ok. This shift is about 1mm but it affects my part.

Can someone help me? it's very urgent, thanks.
Informations:
Printer: Ultimaker 3 extended
SW: Cura 4.4.1
Materials: Ultimaker PLA and natural PVA

[IRobertI 516]

When you say "all grub screws", does that include the ones on the motor shafts? Those are the most common to cause this issue.

[Nidhal Ben Othmen 0]

Actually I didn't check them but I didn't think that it could be the issue because as I said the problem begin in the middle of print. it's perfect just for the first 40% of the model.

[gr5 2,004]

Where it happens is irrelevant.  What is happening is at that spot in the print there is a slightly higher acceleration or jerk.  More important to figure out the cause of the shift.

 

First make sure to oil the 6 rods - as printers age friction can go up.  Feel how much friction it takes to move the head around.  Really feel it so that you can remember it.  Then add one drop of oil to each of the 6 axes and feel it again.

 

Most commonly it's one of the 6 set screws on the axis that is slipping (12 in total).  You may have gotten a nice hex driver with your printer (or maybe not).  If you did you can access all 6 without taking anything apart.  If you *do* have to take anything apart it would be to remove that corner cover (only 2 screws) and pull out the stepper to get at that hardest of them.

 

You can also mark each shaft and each pulley to see if any of them are slipping but it's usually the one on the motor which is also the hardest to get to.

[gr5 2,004]

Alternatively you can put this off, lol.  Just lower the speed to about 1/4 speed when it's getting close to the bad spot.  1/2 speed is often not enough.

[Nidhal Ben Othmen 0]

@gr5 Thanks a lot for this detailed explanation, I'll check it today and keep you in touch 😉

 

[gr5 2,004]

By the way, if you tighten those set screws you want to really tighten them HARD.  If you are using an angle allen wrench it should hurt your fingers when using the torque of the short part of the L.  The shaft should actually twist a bit.