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Z wobbling and shifted layer on overhangs  

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Thomas Cheng
(@thomas-cheng)
Active Member
Z wobbling and shifted layer on overhangs

I finished building my mk3s+ a few weeks ago, and I noticed that regardless of the nozzle I used, 0.25, 0.4, and 0.6, I have issues with unsteady walls, and I get this massive shifted layer on arched overhangs on all my benchys. I have my printer set up on an ikea lack table which vibrates considerably while printing, but I've read online that this shouldn't be that big of an issue.

Postato : 19/01/2023 7:03 am
Diem
 Diem
(@diem)
Illustrious Member

That looks like a belt tension issue (and possibly drive pulley grub screws but check tension first.)

Lubricate your smooth rods and try tweaking the belt tension.

Make your next print this:

https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

It MUST be printed in Prusament PETG or the spring tension will be wrong.

Cheerio,

Postato : 19/01/2023 3:11 pm
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

Purchased some prusament petg, will reply in 1-7 days, thanks.

Postato : 19/01/2023 3:32 pm
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE:

I got a friend to print the tensioner tool for me, and it turns out that all my belt tensions were in the min. I adjusted it to be in the 75% max, 25% min sweet spot, hopefully that works. Am printing some boats right now 😀

I honestly think that Prusa should consider adding these tensioner tools as standard to diy kits, I spent a good hour fiddling with the belt tension and I still fell short.

Postato : 31/01/2023 1:25 am
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

The issues are still present, any more ideas?

Postato : 01/02/2023 3:20 am
Diem
 Diem
(@diem)
Illustrious Member

No improvement at all?  Please show updated pictures including the underside of the model.

Cheerio,

Postato : 01/02/2023 4:31 am
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

Postato : 01/02/2023 5:11 am
Diem
 Diem
(@diem)
Illustrious Member

So there is a little improvement but not enough.  Now is the time to check the drive pulley grub screws.

Make certain the screws are aligned correctly and that they have not worked loose.

See step 28 of: https://help.prusa3d.com/guide/2-y-axis-assembly_165795

Then do the same for the equivalent X axis pulley.

Cheerio,

Postato : 01/02/2023 8:10 am
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

I went back and made sure that the worm gears are very tight, snugly aligned with the flat side of the drive pulley, and made sure the pulley isn't touching the body of the stepper motor itself. While the printers are better, there is definitely a bit of unevenness still, especially in the cabin walls.

 

Postato : 03/02/2023 2:33 pm
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

Also, I tried printing a benchy on a solid granite countertop instead of on my ikea lack table to test if the stability was a factor, but it made no discernable difference.

Postato : 03/02/2023 2:35 pm
Diem
 Diem
(@diem)
Illustrious Member

This is a fairly new printer?  And you've been tweaking the build.

I would be inclined to accept the build quality temporarily and use the printer for a while on less critical parts to allow it to run-in and shakedown any slight misalignments from the build; everyone builds their printer slightly differently and they can take a some time to come together.

The benchy is a torture test, designed to show every minor inaccuracy, most prints will be fine at your current standard and you can revisit the benchy in a couple of months when everything has settled. 

A few years ago, before the Mk3 changed our expectations, you would have been bragging about the near perfection of that benchy...

Cheerio,

Postato : 04/02/2023 4:43 am
Thomas Cheng
(@thomas-cheng)
Active Member
Topic starter answered:
RE: Z wobbling and shifted layer on overhangs

It's a fairly new printer. The issue is, I got the prusa mk3 because I heard that it was fairly ToTL right out of the box. However, I'm getting these uneven layers on everything I print, and it's fairly noticeable. 

Postato : 04/02/2023 5:38 am
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