PETG with PLA support default bed temperature - Hardware, firmware and software help

RE:

BarrittWorks — Wed, 05 Feb 2025 18:35:48 +0000

How can we keep our custom filament shrinkage settings active when printing with different filament types as supports?

I receive the warning "Filament shrinkage will not be used because filament shrinkage for the used filaments differs significantly." I'd like to retain the ability to print precisely sized parts (using my measurement-based custom shrinkage settings) without resorting to object manipulation (Scale factors). Ideally I'd like to at least be able to keep the shrinkage setting for the primary material active, and let the support material be slightly off? Not sure. Perhaps no work around (other than scaling the parts).

Unfortunately Prusa does not discuss this in their support document (https://help.prusa3d.com/article/combining-materials-xl_498103).

Any thoughts?

RE: PETG with PLA support default bed temperature

JoanTabb — Sat, 18 Jan 2025 17:42:41 +0000

if you only use PLA for interface layers you should have less chance of the print, failing due to poor adhesion
also consider setting the support interval spacing to 9, to get a better interface surface

if you use a raft, you can keep the PLA, off the build plate you could make the PLA bed temperature to the same as PETG, because it will not be in contact with the bed

regards Joan

RE: PETG with PLA support default bed temperature

Myzerie — Sat, 18 Jan 2025 16:14:06 +0000

As I needed to find this answer to, think I found it here: https://help.prusa3d.com/article/combining-materials-xl_498103

"On the first layer, the heatbed temperature is based on the first material loaded in the print; from the second layer onwards, it is based on the first filament that is loaded on the second layer."

RE: PETG with PLA support default bed temperature

JoanTabb — Wed, 23 Oct 2024 15:27:36 +0000

Looking at your .3mf,
first point, the original STL has errors. it would be a good idea to fix these first
your original setup has both PETG and PLA on the first layer, You could consider adding a RAFT in PLA to isolate the PETG from the first layer.
if you set the interface pattern spacing to '0' you get a solid interface, this should give more support and less distortion of the interface area.
if you change the wipe tower extruder to extruder 5, the wipe tower
should remain attached to the Build plate at the lower temperature.

unfortunately I don't have an XL to test these settings,

regards Joan

cb9d3d70-bedtemp-revised-jt.zip

RE: PETG with PLA support default bed temperature

Cato — Wed, 23 Oct 2024 08:42:53 +0000

Posted by: @joantabb
It's difficult to guess why this is happening without seeing the Project file. please save your project as a .3mf file, then zip compress the zipfile and attach the compressed zipfile to your next post.
do you have any PLA on the first layer? I Use PLA for the support interface layers and PETG for the rest of the supports are PETG, generally this means there are no PLA Areas on the build plate
Have you set the bed temperatures for both filaments to have 80C on the bed at all times? (this is generally OK if you don't have PLA on the build plate! )
If the PLA is set differently to the PETG this may be the root cause of your issue
regards Joan

The bed temperature for the PLA (support) is set to the default 60 degrees. Since the part is printed in PETG I would have thought it remained at the part bed temperature? The project file is attached, but if it is as you say that you actually need to set both filament bed temperature to the one you want throughout the print, then that's obviously the explanation.

I haven't had any luck at all just using PLA (or PETG for that matter) as only the interface layer, since I cannot get the interface layer to stick to the support structure so I tend to print the whole support structure in the 'other' material.

d9e1dbcd-bedtemp.3mf.zip

RE: PETG with PLA support default bed temperature

JoanTabb — Tue, 22 Oct 2024 10:35:23 +0000

It's difficult to guess why this is happening without seeing the Project file. please save your project as a .3mf file, then zip compress the zipfile and attach the compressed zipfile to your next post.
do you have any PLA on the first layer? I Use PLA for the support interface layers and PETG for the rest of the supports are PETG, generally this means there are no PLA Areas on the build plate
Have you set the bed temperatures for both filaments to have 80C on the bed at all times? (this is generally OK if you don't have PLA on the build plate! )
If the PLA is set differently to the PETG this may be the root cause of your issue

regards Joan

RE: PETG with PLA support default bed temperature

Cato — Mon, 21 Oct 2024 06:34:26 +0000

I just started a new print and it's using 80 degrees for the initial layer and then reduces to 60 degrees on 2nd and above layers. This must surely be a bug?

PETG with PLA support default bed temperature

Cato — Mon, 21 Oct 2024 06:00:14 +0000

Hey,

I've printed a lot of PLA with PETG support where the bed temperature has been set as expected (60 degrees). I just now tried the opposite, PETG with PLA support and was surprised to see that the bed temperature is the same (60 degrees). Why is it not set to 80 degrees as is the default for PETG?

Obviously this caused my print to detach after a bit as PETG really needs that extra bit of heat to stick properly.