waynejacobsen
Posts: 4
Joined: Tue Nov 06, 2018 12:32 pm

Bubbles on top layer

Tue Nov 06, 2018 12:48 pm

I'm printing on a TAZ 6, with PETG at temp 235: bed 77 with 20% fill and 10 top layers with fan off. There appears to be randomly placed un-poped bubbles that show as bulges in the top finished layer. Any suggestions on eliminating them.

wirlybird
Posts: 1221
Joined: Sun Jul 17, 2016 1:32 pm

Re: Bubbles on top layer

Tue Nov 06, 2018 1:31 pm

What print speed? PETG does not like fast. Maybe over extruding a little

waynejacobsen
Posts: 4
Joined: Tue Nov 06, 2018 12:32 pm

Re: Bubbles on top layer

Tue Nov 06, 2018 6:30 pm

60 mm/s

wirlybird
Posts: 1221
Joined: Sun Jul 17, 2016 1:32 pm

Re: Bubbles on top layer

Wed Nov 07, 2018 9:46 am

Most likely too fast. I'd start at 35-40mm/s and see how it goes. PETG does not like to print fast.

S3D-Alex
Posts: 254
Joined: Thu Aug 30, 2018 1:23 pm

Re: Bubbles on top layer

Wed Nov 07, 2018 10:42 am

I would agree with slowing down your print speed but I would also suggest making sure your filament is dry. PETG has a tendency to absorb a lot of moisture and it can cause serious printing defects like bubbles.

SusiT140V
Posts: 52
Joined: Sun Oct 30, 2016 5:12 pm

Re: Bubbles on top layer

Wed Nov 07, 2018 2:18 pm

Hi Wayne,
Without photos it's hard to guess.

It's likely to be one of two things -
Delamination due to it being extruded too cool (the surface will have a matt/silk-like finish) - try 240-245°C ,
or moisture - dry a full 1kg reel in a food dryer/dessicator at 55-60°C (or a preheated electric fan oven) for at least 6 hours.

Hope this helps,
Susi.

waynejacobsen
Posts: 4
Joined: Tue Nov 06, 2018 12:32 pm

Re: Bubbles on top layer

Wed Nov 07, 2018 3:22 pm

I did try to attach a photo of the part. I will try slowing print speed and drying filament, then report back, Thanks (photo attached again)

waynejacobsen
Posts: 4
Joined: Tue Nov 06, 2018 12:32 pm

Re: Bubbles on top layer

Sun Dec 09, 2018 2:58 pm

I made the changes suggested so far, to no avail. I hope this photo shows the problem. Keep in mind that except for top layers all other parts of the part works great
Attachments
IMG_4698ne.jpg

TinaNamdev
Posts: 1
Joined: Mon Dec 10, 2018 1:30 am

Re: Bubbles on top layer

Mon Dec 10, 2018 3:02 am

I did try to attach a photo of the part
Capitalvraddhi
Capital Vraddhi

SimpleScott
Posts: 42
Joined: Tue Jan 12, 2016 7:23 pm

Re: Bubbles on top layer

Wed Dec 12, 2018 9:25 pm

PETG sags a lot (does not bridge well). This includes bridging over sparse infill; it just sags down into the gaps.

Recommend you increase infill density, and increase number of top layers when using PETG. Specific to the print in your photo, I’d suggest doubling the infill density. Thicker layers also helps, but denser infill and more top layers are the key.

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