Trouble printing PETG  

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BobinAtlanta
(@bobinatlanta)
Eminent Member

My i3 ML3S prints every filament very nicely except PETG which very often makes a strange lump of plastic usually on the first layer (sometimes later too) which then catches the tip causing a skip.  Where does the lump come from and how do I resolve this?  I believe i read that Prusa parts are PETG, so there MUST be a setting i need to change.  

Thank you for your suggestions!

Bob

Posted : 10/09/2020 9:52 pm
mjlewis37
(@mjlewis37)
Trusted Member

PETG is some sticky, oozy stuff, that's for sure. I'm new to it too, but am getting good prints now. I have an i3 MK3. Textured powder coated PEI sheet.

It sticks to brass and aluminum very well, I quickly got into the habit of brass brushing the nozzle and heatblock before every print. I got an E3D nickel plated copper nozzle and the PETG does not stick to that well. I still watch the nozzle b4 the print and take off as much oozing as I can using copper tongs so as not to hurt the nickel plating.

Settings that I think have helped. I started with the Prusament PETG profile and changed:

Retraction: 2mm

Retraction speed: 50mm/sec

Z hop: still .6mm

First layer speed: 10mm/sec (am toying with 20mm/sec)

Lowered just about all of the faster move speeds to 40mm/sec, even on infills for now. I'll try attaching a pic on my next post of the settings for clarity. Left travel speed at 180mm/sec

Best wishes!

This post was modified 10 months ago by mjlewis37
Posted : 11/09/2020 4:36 am
mjlewis37
(@mjlewis37)
Trusted Member

Posted : 11/09/2020 4:51 am
mjlewis37
(@mjlewis37)
Trusted Member

Oh, and make sure your live z is set well for PETG. If you haven't already, do a first layer calibration and make sure you are laying down a good bead of PETG that you can't easily scratch off with your fingernail.

Posted : 11/09/2020 4:57 am
BobinAtlanta
(@bobinatlanta)
Eminent Member

@mike-l14

I made the speed changes and it worked!  I did not "Retraction, retraction speed or speed hop" because i could not find where to change those settings PrusaSlicer.  Where are they?  I also purchased some fine brass brushes that should arrive from Amazon tomorrow.  

Posted : 12/09/2020 2:12 pm
mjlewis37
(@mjlewis37)
Trusted Member
Posted by: @rbdopp

@mike-l14

I made the speed changes and it worked!  I did not "Retraction, retraction speed or speed hop" because i could not find where to change those settings PrusaSlicer.  Where are they?  I also purchased some fine brass brushes that should arrive from Amazon tomorrow.  

Sweet! My retraction may be a bit much at 2mm and likewise with Z hop, I'll experiment with both lowering both.

You change them in PrusaSlicer under the Printer Setting tab - Extruder 1. (Lift Z = Z hop)

This post was modified 9 months ago by mjlewis37
Posted : 12/09/2020 4:05 pm
mjlewis37
(@mjlewis37)
Trusted Member

I also got what turned out to be a pack of 3 E3D V6 silicone socks for the heatblock. I got the one with the big hole. This to help keep the heater block clean.

https://e3d-online.com/products/v6-silicone-socks-pack-of-3

This post was modified 9 months ago by mjlewis37
Posted : 12/09/2020 4:18 pm
mjlewis37
(@mjlewis37)
Trusted Member

Oh, the Amazon link for the E3D V6 boots, large hole:

https://www.amazon.com/gp/product/B077TKBKR3/ref=ppx_yo_dt_b_asin_image_o04_s00?ie=UTF8&psc=1

Posted : 12/09/2020 4:29 pm
mjlewis37
(@mjlewis37)
Trusted Member

@rbdopp

Saw that you are in the U.S., Harbor Freight has brass brushes for 79 cents each. I found that brushes load up with PETG too, sigh.

So I got the E3D V6 nickel plated copper nozzle that stays much cleaner with PETG.

https://www.amazon.com/gp/product/B07B674TJC/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Copper tongs to help pull off ooz without damaging nickel plating. Gotta love this forum where I was turned onto the tongs:

https://www.amazon.com/gp/product/B07CH36MM2/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

Posted : 12/09/2020 5:54 pm
bobstro
(@bobstro)
Illustrious Member

I use small strips of corrugated cardboard to scrape off most of the gunk that accumulates on my nozzle and heater block. After that, I can use a wire brush, or toothpicks to get in around wires if needed. This keeps most of the crud out of the brushes (I only replace them every few months) and avoids potentially shorting any wires. It's also easier on coated nozzles and blocks. A bit of upcycling cardboard and avoids tossing plastic handled brushes needlessly. Also yields better cleaning results IME.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 12/09/2020 6:06 pm
BobinAtlanta
(@bobinatlanta)
Eminent Member

@mike-l14

They arrive on Monday.  Thanks again!

Posted : 12/09/2020 6:40 pm
mjlewis37
(@mjlewis37)
Trusted Member

@bobstro

Great tip on the cardboard brush Bob.

You probably also mentioned cleaning brass brushes on cardboard. I've been doing that now. I bend a small piece over and tape it together, then brush across the exposed corrugated ends if needed.

This post was modified 9 months ago 2 times by mjlewis37
Posted : 12/09/2020 7:33 pm
BobinAtlanta
(@bobinatlanta)
Eminent Member

@mike-l14

Thanks again!  They arrive next week.  I will hold off printing the parts i need until everything is in place.  Also, where do i change the "Retraction, retraction speed or speed hop" that you suggested?  

Posted : 12/09/2020 8:07 pm
mjlewis37
(@mjlewis37)
Trusted Member
Posted by: @rbdopp

@mike-l14

Thanks again!  They arrive next week.  I will hold off printing the parts i need until everything is in place.  Also, where do i change the "Retraction, retraction speed or speed hop" that you suggested?  

Oh, that is answered above with a screenshot. It is in the "Printer Setting tab - Extruder 1" in PrusaSlicer. Settings I've changed will have an orange unlocked lock icon next to them.

This post was modified 9 months ago by mjlewis37
Posted : 12/09/2020 8:19 pm
BobinAtlanta
(@bobinatlanta)
Eminent Member

@mike-l14

Thank you again Mike!  You are like the professor!  How did you learn to make these changes?  It sure isn't intuitive.  I will do them and report back (next week after the new parts also arrive).  Thank you.  

Posted : 13/09/2020 12:22 am
mjlewis37
(@mjlewis37)
Trusted Member

@rbdopp

LOL! No professor. This stuff still overwhelms me and I think I am going to break the printer any minute. I'm close enough to a newbie to remember the pain. Still experience it. I'm very new to PETG.

Getting that first good layer or print is thrilling with a new type of filament.

This post was modified 9 months ago by mjlewis37
Posted : 13/09/2020 1:26 am
mjlewis37
(@mjlewis37)
Trusted Member

@rbdopp

Oh, I learned the settings from YouTube videos and probably this forum. Trial and error. Funny that one has to change the default Prusa PETG settings. Shrug.

This post was modified 9 months ago by mjlewis37
Posted : 13/09/2020 1:35 am
mjlewis37
(@mjlewis37)
Trusted Member
Posted by: @mike-l14

@rbdopp

Oh, I learned the settings from YouTube videos and probably this forum. Trial and error. Funny that one has to change the default Prusa PETG settings. Shrug.

LOL. I double checked the PrusaSlicer profiles, I'm guessing they are all for PLA. Meaning, there were no PETG profiles for me to change.

This post was modified 9 months ago by mjlewis37
Posted : 14/09/2020 4:53 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @mike-l14

[...] Funny that one has to change the default Prusa PETG settings. Shrug.

You want to make changes for specific filaments in a filament profile. Load one of the default PETG profiles up, tweak it as you see fit and just save it with a new name. Note that the Prusa PETG profiles do provide overrides on speeds.

I personally like to slow down de-retraction speeds with all filaments to avoid non-Newtonian effects during intense prints and also to reduce retraction and z-lift values and disable wiping since calibrating my filament extrusion multiplier reduces the need for so much movement. I've modified my default Mk3 profile accordingly.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 14/09/2020 6:21 pm
BobinAtlanta
(@bobinatlanta)
Eminent Member

@mike-l14

So i cleaned it with my new fine brass brushes, attached the silicon bootie and made all the changes you recommended.  It is printing PERFECTLY!  I taped your screen grabs on my hood where "Jolene" lives.  The name is because my wife calls her "The other woman" because i am constantly checking up on her.  Thank you so much.  I can now print PETG.  YEA!

Posted : 14/09/2020 9:30 pm
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