MotoGP1199
Posts: 6
Joined: Sun Sep 02, 2018 6:46 am

Layer Shift after bridge

Mon Sep 03, 2018 3:58 pm

I'm newer to 3d printing and for the most part have gotten things squared away. However on this piece I'm getting a slight layer shift or variance on layers that have the bridge and layers that do not. It's creating rings around the piece. Not really sure what is changing or how to correct this. Thanks for your help.

eSun PLA+
Nozzle: 224*
Speed: 60 mm/s
Layer Height 0.3
20180903_125030.jpg

briandreger
Posts: 2
Joined: Mon Jan 25, 2021 2:47 pm

Re: Layer Shift after bridge

Mon Jan 25, 2021 2:50 pm

I am having the exact same issue with layer shift on the layers with a bridge.....did you find out the fix ?

zemlin
Posts: 351
Joined: Mon Feb 01, 2016 11:36 am

Re: Layer Shift after bridge

Mon Jan 25, 2021 7:20 pm

What's the wall thickness, nozzle diameter, and extrusion width?

Don't think this is related to your issue, but I battled a ring in a circular part. The part started off with a bunch of legs and several inches up the part they all join. At that bridge point all the legs pulled in creating a ridge in the ID of the part.

Seemed to be that the bridging between legs was contracting and closing the gaps between the legs slightly drawing them all in.

To prevent this from happening I added an external structure that connected to the legs at a very small point right before the gaps bridged. This held the legs in position and resulted in the smooth inside diameter I needed. I then use flush cutting wire cutters to remove the halo when the build is complete.

As I said, this doesn't seem to be what's going on with your part, but in case it might help someone else.
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briandreger
Posts: 2
Joined: Mon Jan 25, 2021 2:47 pm

Re: Layer Shift after bridge

Sun Jan 31, 2021 12:56 am

zemlin...I discovered that my problem was caused by the phenomenon you described.

I had 2.4 mm walls on a box (70x100x20 & no supports) that when the roof (bridge) was printed, it actually pulled the walls in when the bridge strands cooled and shrunk.

so it looks like a layer shift but actually isn't....the walls are pulled in from 90 deg to something like 85 or so...then the top solid layers on top of the bridge continue to print where they are supposed to but the wall has moved...giving the illusion of a layer shift.

the fix, I think, is going to redesign the print or modify the bridge printing parameters, ie speed, cooling, etc.

walls = 2.4mm
nozzle = .6
extrusion width = .65
layer height = .3
PLA @ 220c
Attachments
box.png
box.png (14.47 KiB) Viewed 265 times

Christoph13524
Posts: 1
Joined: Mon Feb 12, 2018 5:03 pm

Re: Layer Shift after bridge

Sun Feb 14, 2021 11:21 am

Hi,

that‘s not a layer shift. This simply is backlash caused by machanical inaccurancy mostly because of (loose) belts.

At the hight where the rectangle holes are the printer moves the head outwards but at the height where no holes are, the head comes from another direction and because of backlash, it is not at the same position.

Tighten your belts or upgrade to GT2 or GT3 belts which have a round profile.

Google backlash if you don‘t understand it. It is hard to describe, especially at your 3d model. There are also some files at thingiverse to see how many backlash you have.

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