PETG questions
Hello,
I finished assembling an MK3S last week and printing in PLA is showing no major problems so far.
I tried to switch to PETG and it seems to be a much more difficult material. I am using an AmazonBasics PETG spool and I slice using the Prusament PETG settings. I have several (newbe) questions.
1) Do you have to recalibrate the distance between nozzle and bad with a new material? The original calibration was done with PLA.
2) Print after print and without changing settings there is an inconsistency with the first layer. Sometimes it prints greatly other times it just doesn't stick to the bed.
3) I printed several times a planetary gear model. While all my tests in PLA roll without much friction, in PETG they roll with more difficulty. Is it a problem with the print or just a property of PETG
What do you think?
RE: PETG questions
Hi,
No, you do not have to recalibrate, or at least i haven't. You have to do it only if you change the bed for the rugged one
PETG is more difficult to print, specially the adhesion to the bed, you must use an stick bar in the bed if you are using the normal one, not rugged, since it will stick so hard that it can damage the bed taking it out. Even with the sticking bar applied i had a hard time taking it out
Don't have many experience with PETG though but hope it helps
RE: PETG questions
Hi,
i had no issues with my first PETG prints at all. Other than masterhead said I would try to recalibrate the first layer for PETG as in my experience it does not like to be squished so much as PLA does. So I suggest to raise the nozzle a bit.
Kind regards
RE: PETG questions
You might back off (make less negative on the Mk3) your Live-Z adjustment for PETG. 0.2mm is commonly suggested, though I go with less myself. The reason is that PETG doesn't require as much of the 1st layer squish for good bed adhesion, and has an affinity for sticking to the nozzle if it scrapes the surface. If printing at 240C or below, glue stick is not necessary. You can spray some Windex or wipe your fingers on the PEI surface to reduce adhesion. Glue stick is useful for higher temps.
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RE: PETG questions
I am using an AmazonBasics PETG spool and I slice using the Prusament PETG settings.
You might want to try a different PETG setting for that filament. Prusament PETG likes it hot and uses 240/250 and 85/90 for temps which may be a cause of your problems. Try with the basic PETG setting or modify the temp settings and save a copy. I use the NGEN or Generic PETG settings for that filament and it works well.
I have also used 5-6 rolls of Amazon Basics PETG and find 230/235 and 80/85 sufficient. and it is not bad PETG at a decent price too.
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RE: PETG questions
Thanks for all your answers it's very interesting 🙂
RE: PETG questions
@bobstro, Wow. I see the life adjust Z setting. Many questions are popping up 🙂
1) Is this tuning memorised for the subsequent prints or is this just for the duration of the current print?
2) What is the relation between life adjust Z and "First layer hight" in the Print Settings of PrusSlicer?
@jbinfl Thanks for the tip. I will try your settings
RE: PETG questions
@bobstro, Wow. I see the life adjust Z setting. Many questions are popping up 🙂
Good! All of this gets a lot easier as you get more comfortable with how the different settings inter-relate. You don't want to chase one problem only to realize later you've introduced others.
1) Is this tuning memorised for the subsequent prints or is this just for the duration of the current print?
The Live-Z adjust should be memorized by the printer. You can look for it under Settings on the front panel menu (right after the Raspberry Pi setting). You do still want to run the on-board Prusa routine to completion as -- at least at one point -- there reports that doing so set a flag indicating that the procedure was complete which allowed storing of new values.
2) What is the relation between life adjust Z and "First layer hight" in the Print Settings of PrusSlicer?
Ah, good question. Live-Z tweaks the physical gap between the print surface and nozzle tip. This is your printer's "0" position. Too high and nothing will adhere. Too low and you mash the filament into the print surface, getting a rough 1st layer finish and possible extruder clicks and jams. Side note: Mesh bed leveling attempts to identify additional tweaks to this setting to conform to any bed irregularities over the entire print surface. Enable 7x7 mesh bed leveling in settings for more accuracy.
The 1st layer height is how far above that 0 position the 1st layer should print. Other layer heights are the specified distance above that. In reality, your printer won't go lower than 0.15mm with normal move commands, so that's an effective minimum 1st layer height that's not really documented. anywhere.
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He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: PETG questions
You don't want to chase one problem only to realize later you've introduced others.
Yes, absolutely. I am now busy trying to level correctly the PEI sheet. It's not as easy as it seems.
I ended up with a Bed level correction that to me sound excessive:
left -90um
right 90um
front 60um
back -60um
Therefore I am considering disassembling the heated bed and repositioning it, this time applying a gentle torque to the screws and making sure that it is distributed evenly.
You live to learn 😀