stiandahl
Posts: 7
Joined: Sun Feb 23, 2020 2:14 pm

PETG Issue

Sat Sep 19, 2020 3:30 am

Hey Guys!

I'm having alot off issues with printing with PETG. I Have tried all settings I can think off, but still havent found the right one. My prints with PLA turns out perfect, but PETG is a mess every time. The part separates and look like a mess. I have attached an image of a Lego brick print. As you can see, the studs are falling off, and the print looks bad.
Any ide??

(Excuse ny English)

Kind Regards
Stian
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RoboDLC
Posts: 80
Joined: Sun Apr 23, 2017 2:30 am

Re: PETG Issue

Mon Sep 21, 2020 7:20 pm

Yeah, PETG is a completely different beast from PLA.
Comments and hints.
Ditch the raft, that is a waste of time and material. Get your bed level and you won't need it. Leveling is an hour or so of time that you will not regret doing.

PETG prints hotter, both in bed and nozzle temperature.
Unless you have a perfectly tuned printer and can turn up the heat to print fast, don't try to print fast. That is an order of magnitude harder to do then just printing well.
So. Try each one of these, one at a time, to see which one does the trick. I would leave the each step on as you try the next step.

Drop your print speed, if your base is 80mm/s in PLA, drop to 60mm/s. (then go down the wall/infill/support list 60%, 80%, 80%)
Do NOT squish PETG. Do a 150% layer height on the first layer. I do 150% layer height and 110% trace width. (With CURA I up the flow).
Heat your bed to 75 or 80C (Or don't heat at all and use Blue Tape).
Take your PETG up to 230 or 240C at the nozzle, I select the middle of the brand's temperature range as a starting point.
Depending upon your PETG manufacturer and part fan or blower, you will want from 60 to 100% part fan. I often just go 100%, not always.
Turn on coasting, at least .2mm
Turn on wiping, 2mm works well for me MOST of the time.
On the advanced tab, select retract during wipe.
On the advanced tab, select avoid crossing edges, about 3mm is a good start for the max distance.
Finally, Turn off z-hop, this is often the best way to eliminate stringing, but is not always needed.

As long as your bed is level, as you go through this list, things will get better and better. There are other settings to play with, but these will get you on your way I think.

DLC
D. Clark
Robotics and sensors engineer
And lots of other stuff for fun.

stiandahl
Posts: 7
Joined: Sun Feb 23, 2020 2:14 pm

Re: PETG Issue

Tue Sep 22, 2020 12:49 pm

Thanks alot for a great answer!

Just one thing, I cant find the Z-hop setting. Which tab is it on?



Thanks again. Have a lot of thing to try out now.

P.S. Do you have a suggestion for a test print, or maby a link to a stl file? :lol:

RoboDLC
Posts: 80
Joined: Sun Apr 23, 2017 2:30 am

Re: PETG Issue

Wed Sep 23, 2020 12:13 am

Sorry,

S3D calls it Retraction Vertical Lift, and its on the first tab, Extruder.
thingiverse.com, get the simple XYZ cube. Simple and tests a bunch of things.

DLC
D. Clark
Robotics and sensors engineer
And lots of other stuff for fun.

DebraInore
Posts: 3
Joined: Fri Sep 18, 2020 8:53 am

PETG Issue

Tue Sep 29, 2020 7:22 am

Thanks Mike for the good work and the really fast reaction on this, today is opening night and Ill test the new version

Best regards
Jörg
http://xevil.net/

anthonyoc
Posts: 2
Joined: Thu Oct 01, 2020 10:59 pm

Re: PETG Issue

Thu Oct 01, 2020 11:15 pm

I'm having similar problems but only with S3D software on the Flashforge Guider IIS. When I print a simple little cube using FlashPrint (Flashforge software) with a raft, I get a reasonably good result. The raft still sticks a bit hard to the model but its usable.

When I print the same part using S3D (aligning the settings as much as possible with the FlashPrint settings), the 1st layer of the raft comes out quite flimsy so the upper layers tend to separate allow the part to warp up and away from the platform.

The FlashPrint raft seems to be much better structured (possibly because it's possible to change the infill % in the first layer) but I may be missing something in the settings. I know some people will suggest no raft but without one, the part doesn't stick to the platform at all, even with glue.

Current settings are:
Extruder: 230°C
Platform: 80°C
Base print speed: 50mm/s
Layer height: 0.1mm
First layer height: 0.2mm
Perimeter: 3 shells
Top layers: 4
Bottom layers: 4
Overlap: 30%
Infill: 25%
Separation to model (raft): 0.2mm
Cooling: On after 1st layer
Extrusion multiplier: 1.1
Retraction distance 1.3
Retraction speed: 30mm/s

Suggestions very much appreciated.

RoboDLC
Posts: 80
Joined: Sun Apr 23, 2017 2:30 am

Re: PETG Issue

Fri Oct 02, 2020 2:31 pm

If you don't stick without a raft. You will get nowhere until you do. The very first step to successful printing is the first layer. The raft is a bandaid, your first layer problem has to be fixed. Take the time to level your bed. Do it when both the bed is hot (the geometry changes with heat) and when the hot end is hot (so you don't have plastic on the nozzle distorting your efforts).
Really.
You must have a level bed so you get a well sticking first layer before you will get a reliably good print.

Second item. PETG does NOT like to be squished. Your first layer should be .3mm, not .1.
Your flow of 110% on the first layer will get the "squish" down.
30% infill overlap is overkill. 15% should be fine.
Your retract of 1.5mm is OK if you are direct extruder, for Bowden, you may need to go as high as 3mm.
I like high-speed retractions. Mine are usually 40-60mm/s. YMMV
How much fan you will need depends upon a lot of things. On layer 2+ I have used from 50% to 100% depending. Blowers will push harder, you may need to dial back, fans are pretty weak, you may need to go to full on.

DLC
D. Clark
Robotics and sensors engineer
And lots of other stuff for fun.

anthonyoc
Posts: 2
Joined: Thu Oct 01, 2020 10:59 pm

Re: PETG Issue

Fri Oct 02, 2020 6:24 pm

Thanks for all the advice. I'll focus on that first layer to get it right. Aside from the first layer, the print is very accurate and doesn't suffer from any stringing or distortion.

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