mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Layer tearing in specific areas near perimeter start

Sat Aug 22, 2015 2:28 pm

I have a model that often suffers from some really nasty looking horizontal "tears" where it looks like some layers are not bonding correctly at the beginning of the outline perimeter. These occur in the same approximate area every time but I don't see any problems in my STL or gcode preview that would make me suspicious. Here's a photo of what I'm getting when things go really bad, but on the best prints there is always at least a trace of a line here.

Any advice on things to try to remedy this? I've checked my mesh in a few different apps and even tried smoothing the detail in this area a bit to be safe, but the problem persists.
IMG_5185.JPG

mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Re: Layer tearing in specific areas near perimeter start

Sat Aug 22, 2015 2:51 pm

Looking more closely at the preview I think I see the culprit. The slicing appears to be creating isolated "top layers" along sloped areas of my outline as it curves towards the top of my model. Is there some setting I can adjust to prevent this from happening?
toplayers01.JPG

CompoundCarl
Posts: 2005
Joined: Wed Aug 05, 2015 7:23 am

Re: Layer tearing in specific areas near perimeter start

Sat Aug 22, 2015 6:34 pm

It creates those to make sure you have the correct number of top solid layers, so it's normal behavior. For example, if you had a very shallow angle, it needs to add those solid layers in there to make sure that you always have the right number of solid layers when looking top-down through the part.

So if you want to reduce that, you can decrease the number of top solid layers for that section of the print. Or add more perimeters, since I think that also helps get more solidity on the walls.

mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Re: Layer tearing in specific areas near perimeter start

Sun Aug 23, 2015 1:52 pm

After some more tests I don't think this was the real issue. Any ideas what might be causing these rips?

JoeJ
Posts: 1436
Joined: Sun Feb 16, 2014 10:52 am

Re: Layer tearing in specific areas near perimeter start

Mon Aug 24, 2015 7:31 am

I've seen gaps in my prints that look exactly like that before. They were almost always caused by the extruder acting up. Anytime you have small portions of the print where it randomly stops extruding, it's usually the extruder.

As an extra check, you can look at the gcode in the previewer. If there aren't missing perimeters in the preview, but they are missing in the actual print, then it's most likely an extruder issue.

mitchfx
Posts: 184
Joined: Fri Feb 27, 2015 6:01 pm

Re: Layer tearing in specific areas near perimeter start

Mon Aug 24, 2015 11:01 am

Yeah, that makes sense...but why would it always show up in the exact same areas print after print?

JoeJ
Posts: 1436
Joined: Sun Feb 16, 2014 10:52 am

Re: Layer tearing in specific areas near perimeter start

Mon Aug 24, 2015 1:21 pm

How "exactly the same" is it? Can you show pics of 2 different prints side-by-side? Preferably two that used the exact same gcode.

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