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Printing with PLA and PETG  

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wybielacz1
(@wybielacz1)
Active Member
Printing with PLA and PETG

Hi,

so i was only printing with PLA till now, but now from time to time i want to print some models with PETG. 

I was wondering if there is something which i have to look after when i do the switch? Do i just simply switch the material from PLA to PETG and print and then just switch back? Can this make any issues or is there any special handling required?

 

Posted : 31/08/2020 9:42 pm
jsw
 jsw
(@jsw)
Noble Member
RE: Printing with PLA and PETG

I do not have the Mini, but in general for 3d printers, the slicer program (PrusaSlicer, Cura or whatever) is what sets the temperature and other parameters for the type of filament.  There's really nothing on any printers that I'm familiar with that needs to be set or set back when changing type of filament.

When loading or unloading filament, however, I'll always preheat to the approximate temperature before loading or unloading.

Posted : 31/08/2020 10:30 pm
mark
 mark
(@mark-3)
Estimable Member
RE: Printing with PLA and PETG

I've found not so much of an issue going from a colder to a hotter filament, as the higher temperature pushes out the lower temperature melting filament. When going from a hotter to a colder filament, I've seen underextrusion and some of the hotter filament was stuck in the extruder. To fix that, I load the cooler temp filament, then go into the settings menu and set the extruder temp to the high end of the previous higher temp filament. Then I go to the move axis menu and move E (extruder) a few numbers. That effectively purges at the higher temperature and you will see some of the color come out from the hotter temp filament.

Occasionally, I have to do a cold pull with the cooler temperature filament, starting at the high end temperature of the hottest filament that was used before.

I know some people that do a cold pull on every filament change. It is a little harder to do with the Bowden extruder. I don't want to unscrew the fitting too many times.

Use the cool down menu selection when done with this to avoid cooking the cooler temp filament for hours.

Regards,

Mark

Posted : 01/09/2020 2:13 am
jsw
 jsw
(@jsw)
Noble Member
RE: Printing with PLA and PETG
Posted by: @marklgoldberg

When going from a hotter to a colder filament, I've seen underextrusion and some of the hotter filament was stuck in the extruder.

I learned the lesson on this when printing with PC Blend, letting it sit overnight, and trying to print with PLA.  The PLA refused to load.

I didn't have to do a cold pull (I do have the special cleaning filament and have done it) but I did let it get stable at 270 or so and flushed the remaining PC Blend out.

I haven't had this issue when going from ABS to PLA, which I do often, only with the PC Blend.

Posted : 01/09/2020 7:11 am
Gordon W
(@gordon-w)
Reputable Member
RE: Printing with PLA and PETG

If you are swapping between the smooth and textured sheet don't forget to adjust your live z height each time as one sheet is thicker than the other.

Posted : 01/09/2020 9:05 am
wybielacz1
(@wybielacz1)
Active Member
Topic starter answered:
RE: Printing with PLA and PETG

I actually only have the smooth sheet, is it also ok to print PETG on the smooth sheet? 

Posted : 01/09/2020 3:12 pm
Gordon W
(@gordon-w)
Reputable Member
RE: Printing with PLA and PETG

@wybielacz1

I haven't started with printing PETG yet, so have no experience but I understand that PETG can stick to the smooth plate too well and damage the plate when the print is removed. I'm sure others in the thread will offer advice on the best methods, but glue stick is often recommended as a separating agent.

Posted : 02/09/2020 11:24 am
jsw
 jsw
(@jsw)
Noble Member
RE: Printing with PLA and PETG

Yes, PETg prints quite well on the smooth sheet.  I might suggest a release agent.

Posted : 02/09/2020 11:28 am
bobstro
(@bobstro)
Illustrious Member
RE: Printing with PLA and PETG
Posted by: @wybielacz1

I actually only have the smooth sheet, is it also ok to print PETG on the smooth sheet? 

Most PETGs will print just fine on the smooth PEI provided you use a release agent. Prusa recommends a spray of a clean sheet with Windex. A few wipes of the fingers usually works well too.

Although it may seem counterintuitive, you want the bed thoroughly clean to ensure an even application.

One exception is if you use high temperature PETG (e.g. 3DXTech) that print at 250C or higher. For these, I do use the glue stick. MagiGoo also works well. Other temp sensitive adhesion agents may also work well. 

Consider dedicating one side to PETG and the other to PLA for convenience.

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 : 02/09/2020 2:01 pm
mark
 mark
(@mark-3)
Estimable Member
RE: Printing with PLA and PETG

My solution is lots of Windex for thick parts and a combination of Windex and a glue stick for thin parts:

https://forum.prusaprinters.org/forum/hardware-firmware-and-software-help/pei-sheet-damaged-with-first-print/paged/2/#post-241306

The ratio of glue stick to Windex determines how much it sticks. More glue stick sticks less.

Regards,

Mark

 

Posted : 02/09/2020 2:09 pm
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