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Extremely bad layer shifting!  

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gluons5439
(@gluons5439)
New Member
Extremely bad layer shifting!

I recently just finished building my robotics team’s MK3s, and on first prints, there was bad layer shifting. First print was the preloaded Benchy, and second was the castle. The belts tightness are in the range on the instructions, and the grub screws are tight on the motor shafts. Could it be a firmware issue? 

This topic was modified 5 years temu by gluons5439
Opublikowany : 22/11/2019 7:09 pm
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Illustrious Member
RE: Extremely bad layer shifting!

What are the belt numbers?

Post a photo of a shifted print.

 

Opublikowany : 22/11/2019 9:44 pm
gluons5439
(@gluons5439)
New Member
Topic starter answered:
RE: Extremely bad layer shifting!

https://imgur.com/a/rOfFsi2

it’s on both axis, and the belt numbers are within the 2 numbers from the website.

Opublikowany : 01/12/2019 7:45 pm
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(@)
Illustrious Member
RE: Extremely bad layer shifting!

Run a self test.  Read the belt tension display. Write the numbers down  and post them.

If the tension numbers are below 260 you have friction problems.  Either bearings are dry, or something is too tight and distorting them.  The tension numbers should be high, mine are above 290.

It also might be a loose drive gear, as most folk don't understand how to tighten set screws properly.  And it might be a loose belt.  And no, the belt tension numbers have nothing to do with belt tension (Prusa is wrong).  

 

Opublikowany : 02/12/2019 1:45 am
gluons5439
(@gluons5439)
New Member
Topic starter answered:
RE: Extremely bad layer shifting!

@tim-m30

X218

y286

what confuses me is that X is not normal, but it’s both axis shifting

Opublikowany : 02/12/2019 2:22 am
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(@)
Illustrious Member
RE: Extremely bad layer shifting!

218 is a horribly low number and means you have a serious problem to solve.

Did you grease the bearings when you installed them (they need to be packed with grease before placing them on the rods)?  If not, with those numbers I'd even suspect you damaged a bearing during install.

But, assuming it is a simply dry bearing issue, remove the print sheet, cover the heat bed with paper towels as a drop cloth, and apply oil to the two rods and work the extruder back and forth until the X axis moves smoothly and freely.  Gravity should be enough to cause the extruder to slide side by side - lift the left, it slides right; lift the right, it slides left.  Same for the bed, though it tends to slide more easily.

If oil frees up the motion, plan on tearing the printer apart to lube the bearing; you are seriously risking damage to the rods = if they haven't already been damaged.

One other source of excessive friction is the extruder housing has been known to deform bearings if the screws near the bearings are too tight.  Try loosening them (I think there's five screws need to be backed off).

You can't tel from a part which axis is shifting unless it's a single shift (aka crash).  If the motors are stalling every other cycle, you will get some nasty looking results that seem to be X and Y because diagonal moves will be affected.

 

 

Opublikowany : 02/12/2019 5:48 am
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