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Printing with PETG

Posted by calaban 
Printing with PETG
November 11, 2019 03:46PM
I'm having terrible print quality with PETG. I'm using 3d Solutech PETG. I can get good consistent first layer sticking and anything that is printed in vase mode come out great. The issues arise when you try to print anything with infill is where the trouble starts to appear. I'm having a terrible blobbing issue when the infill starts to print. There are blobs being deposited in pretty much the same spots and PETG collecting on the nozzle. The problem gets worse as the layers go higher. Whenever there is a direction change is where the problem is most apparent.

I'm not sure what settings I need to start with. I've been trying speed, nozzle temp, and FAN. Nothing seems to reduce the blobbing to a point where I'm getting successful prints. The only thing I have not done much with is the retraction distance and speed.

I'm printing between 215 and 230 degrees. Nothing seems to help with the blobbing. Stringing isn't too bad. My PLA prints are fine.
Re: Printing with PETG
November 13, 2019 01:39PM
Quote
calaban
I'm having terrible print quality with PETG. I'm using 3d Solutech PETG. I can get good consistent first layer sticking and anything that is printed in vase mode come out great. The issues arise when you try to print anything with infill is where the trouble starts to appear. I'm having a terrible blobbing issue when the infill starts to print. There are blobs being deposited in pretty much the same spots and PETG collecting on the nozzle. The problem gets worse as the layers go higher. Whenever there is a direction change is where the problem is most apparent.

I'm not sure what settings I need to start with. I've been trying speed, nozzle temp, and FAN. Nothing seems to reduce the blobbing to a point where I'm getting successful prints. The only thing I have not done much with is the retraction distance and speed.

I'm printing between 215 and 230 degrees. Nothing seems to help with the blobbing. Stringing isn't too bad. My PLA prints are fine.

PETG is a different beast from PLA. Here are things that I do to reduce stringing and blobbing:
Enable "coasting". This stops filament from being extruded for the last "little bit" of a line deposited.
Enable wiping, if you can. This causes the head to backtrack a bit before it starts a travel to a new line.
Don't z-hop during a retract. This reduces oozing during the travel.
Minimize the retracts done. There are usually settings where you can specify how long a line is required before a retract will be done.

Try the settings in the order I listed. I get pretty good PETG results these days. I know that both CURA and Simplify3D can spec some of these settings.

DLC


Kits: He3D K200 Kossel, Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head
Scratch: Large bed Cartesian, Linear slide Delta, Maker-Beam XL Micro Delta
Re: Printing with PETG
November 14, 2019 10:34PM
I was having so much trouble with sticking and blobbing. I think I have many of my issues solved. Running the heat bed hotter helped with the adhesion, I turned it up from 60 to 70c.

As for the blobbing I enabled the coasting in Cura and adjusted the settings to .6^3 so that really reduced the blobbing.

I'll try the wipe again.

"Minimize the retracts done. There are usually settings where you can specify how long a line is required before a retract will be done."
Not sure where that is in Cura, but I will fish around.

Thank you for the suggestions. PETG is nice and strong but wow, not as easy as PLA.
Re: Printing with PETG
November 15, 2019 02:51AM
I print PETG exactly the same as I print PLA except for indicated bed temperature increased from 70C to 80C, nozzle temperature increased from 200C to 245C, and print cooling fan either off or at 30%. I don't use coasting, it is a poor substitute for pressure advance.

Edited 3 time(s). Last edit at 11/15/2019 02:53AM by dc42.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Printing with PETG
November 18, 2019 11:51PM
I think the root of my issues came down to width and height. I'm using a .6 nozzle and I nearly maxed out the width to .84 and taller layers seems to yield much better results. My last print was at .42 layers, which seem to be having some good results.
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