Weird first layer print behaviour

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gizmo91
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Weird first layer print behaviour

Postby gizmo91 » Tue Sep 05, 2017 12:45 am

Here's a challenging one.

See the pics below, but something bizarre is happening on the first layer.

It prints the shells, and then starts the first solid layer, usually around the middle of the print (red line), from that point until the edge of the print the filament is wavy (direction of red arrow), but then the extruder moves to fill in the other half of the first layer and it prints fine like its supposed to (direction of green arrow). So why would it print all wavy at first, but then once the head moves, it prints the rest of the layer fine? It then moves to a new part and again prints wavy at first, then prints fine.

The pictures tell the better story.

Any input would be appreciated!
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20170905_003519413_iOS.jpg

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walshlg
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Re: Weird first layer print behaviour

Postby walshlg » Tue Sep 05, 2017 2:18 pm

you may have your z too small. FWIW I suggest always add a skirt making it easy to check bed leveling and first layer thickness and adhesion.

also if you have a dual head, make sure that this isn't the 2nd head nozzle dragging

gizmo91
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Re: Weird first layer print behaviour

Postby gizmo91 » Tue Sep 05, 2017 9:57 pm

It has nothing to do with bed level or Z height, as it prints the first part crappy and the second part fine all in the same area, and it occurs on different parts of the bed as shown on the picture. If all the red lines where in a line then I'd say bed level, but its everywhere on the bed.

Clearly something is happening between the first part of the first layer, and the second part of the first layer when the head moves to complete it. I just can't figure out what it is.

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walshlg
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Re: Weird first layer print behaviour

Postby walshlg » Wed Sep 06, 2017 2:12 pm

may want to go back to printing cube and towers to see if you can figure out which axis is bad, perhaps the head is binding going in one direction?

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Julia Truchsess
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Re: Weird first layer print behaviour

Postby Julia Truchsess » Wed Sep 06, 2017 3:27 pm

Really a long shot, but worth eliminating in your troubleshooting nonetheless: spool drag may be higher in the "bad" direction.

gizmo91
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Re: Weird first layer print behaviour

Postby gizmo91 » Thu Sep 07, 2017 12:26 am

Ruled out spool drag, pulled out a lot of extra filament and its still doing it. Didn't think of that at first, so good suggestion.

Regarding the bad axis theory, sort of doesn't match as the full layer is placed, if there was a bad axis it would be short in that direction.

I'm thinking retraction. It retracts the filament when it moves, so something is causing it to over extrude when it starts, and then after retraction, it prints fine. But have no idea - hoping Jetguy has a theory.

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Julia Truchsess
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Re: Weird first layer print behaviour

Postby Julia Truchsess » Thu Sep 07, 2017 1:01 am

What material, temperature, and profile?

EldRick
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Re: Weird first layer print behaviour

Postby EldRick » Thu Sep 07, 2017 2:01 am

What slicers have you tried? Anything besides iM?

gizmo91
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Re: Weird first layer print behaviour

Postby gizmo91 » Thu Sep 07, 2017 11:50 am

Raise3D Colorful PLA at 225, 0.30 first layer height, 25mm/s travel speed.

I haven't tried other slicers, but good suggestion, will run a test tonight using S3D

EldRick
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Re: Weird first layer print behaviour

Postby EldRick » Thu Sep 07, 2017 3:49 pm

I'd also try printing with the piece lowered a fraction of a mm in Z, on the theory that perhaps the bottoms of the pieces are not completely flat.

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walshlg
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Re: Weird first layer print behaviour

Postby walshlg » Mon Sep 11, 2017 3:02 am

disable steppers and make sure you aren't getting any binding ofthecarriage

gizmo91
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Re: Weird first layer print behaviour

Postby gizmo91 » Sun Sep 24, 2017 12:10 pm

SOLVED (?)

When I raise the print temp by 5 degrees the issue went away. Not sure why that works, but maybe before the movement more heat is applied which is why it would print some parts good some parts bad. May need to replace my temp sensor as I've always printed at 225C for the R3D premium, now I'm up to 230C to fix the issue.

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Noren
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Re: Weird first layer print behaviour

Postby Noren » Wed Sep 27, 2017 8:09 pm

I have seen this when the nozzle is a little to close to the bed. And why it doesn’t appear all other the place I can’t say. But I think that the 5° increase solved it for you because the plastic flows easier. I think relevelling the bed might have solved it for you as well. (Or it can be so easy that the spools differ in composition ever so slightly from batch to batch.)


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