How to slice for PETG with PLA supports?
I've heard people mention using PLA as the support material for PETG and PETG for PLA. As my attempt PVA was a mess I decided to give this a try while slicing some PETG parts last night. My workflow:
- Selected the MMU2S profile
- Added the parts to the build plate and selected tool 1 which was set to PETG.
- Selected "build enforcers only" for the support configuration.
- Added the desired support enforcers to the parts.
- Selected tool 2 for the support enforcer's extruder which was set to PLA.
When I sliced the model, both the parts and supports were all tool 1 and there was no wipe tower. I checked the settings and found the wipe tower disabled. When I try enabling it (or changing the default support and support interface extruders) it gave me an error that seemed to indicate that it only supports a wipe tower for a different material for supports when the material is soluble. I could force the part and supports to slice as different materials, but it would not generate a wipe tower.
So how is it people are slicing for an alternate non-soluble material for supports and getting a wipe tower to properly purge between tools?
RE: How to slice for PETG with PLA supports?
I've had some luck with this in the past. Some pointers:
- The wipe tower error is because the WT layers need to align with the main print layers. Set support interface distance to 0.
- I think it only uses the support material for the *support interface* layer, not all of the supports. Be sure to set that to a value >0 (I have used 2-3) Makes sense because it's silly to do a toolchange every layer only for bulk support, when all you need is a different material at the interface.
- Edit: regarding the above - don't set the extruder for your support enforcer, go to the print settings, and choose Multiple extruders, then set the support material *interface* extruder to something other than 0.
- Interface layer spacing to 0. This gets you a nice smooth top surface to build on. (See number of layers above, you want 2-3 so it evens out after bridging over the bulk support structure.
- It helps if you use higher temp PLA and a lower temp PETG, to avoid temperature issues (since PS doesn't handle material changes very well). I used PLA+ which could print at 230 and went a little slower on the PETG so it could print at the same temp.
- You need to purge a ton. I mean, A TON. All traces of the other material must be purged or your part will snap at that transition layer.
If there are only a few layers - an awesome tip I picked up is to set up for soluble supports (i.e. 0 interface distance), insert a pause after the final support interface layer, and then color the top of the support with a permanent marker. You'll get an incredible bottom finish, and the permanent marker breaks the bonding enough that it easily separates from the part.
RE: How to slice for PETG with PLA supports?
Yes you need to do a TON of purging, any traces left even the smallest ones will cause layer adhesion issues.
Here is what i do when i print in PLA and use PETG as support:
Preparation:
Go to filament settings and pick your petg profile to prepare as support material.
Go to advanced and check Soluble material, if needed adjust temp and then save as a new profile so you know this is only for petg as support.
(i had to do it like this or slicer would not do the right thing when you pick soluble interface)
When you want to print something:
make sure you have your fake soluble material loaded in slot 5 (this is where the support goes by default)
pick one of the default profiles with soluble interface in the name.
then slice as normal.
this is the basic steps i do, but note that it is not perfect.
the whole point of using petg as support for pla is that they don't stick well together and that also applies to the support structure itself.
so depending on model the first support interface layer may not stick well but usually it works out once the rest of the support interface is created.
also due to the temperature changes you must be careful during filament swaps, it is possible to get a "fake" soft clog in the nozzle caused by leftover petg that was not purged out properly and then get left in the nozzle and after a few swaps it stops completely.
and you definitely want to use a pla that can be printed at a bit higher temperature, ideally closer to where petg will come out of nozzle without any issues.
RE: How to slice for PETG with PLA supports?
@vintagepc, @torbjorn-j3
Thanks for the tips. I finally had another PETG print that needed supports and it's running now. With your guidance I got it use PLA for the support interface without a hassle. Hopefully the print itself goes as smoothly.
I'm using fairly contrasting colors so it will hopefully be easy to tell if I purged enough or not (under the advance settings I set the relative values to 800). If not a few weak layers shouldn't hurt this print as the layers will be under a compression load rather than tension or torsion.
RE: How to slice for PETG with PLA supports?
Yea you need to have crazy purge volumes if you want to have same layer adhesion as a single colour print:
https://www.antalife.com/2020/07/project-just-how-multi-material-is.html
You don't really notice the effects of layer adhesion strength with larger models. But if you do have some thin walls or small features then definitely be wary of it
www.antalife.com
RE:
Using PLA as support material for PETG is the bomb! I've been struggling with getting PETG to print cleanly with supports. I just got the MMU2S and was able to get the settings right, and the results are so smooth and beautiful. The PLA supports remove easily and cleanly. This ROCKS!
FWIW I set the wipe tower to 30mm - really helped with the print time. I'm using matte black PETG and silver PLA and you can see that this is sufficient.
RE: How to slice for PETG with PLA supports?
@gnat May I ask the stupid question, why would you want to do that? If it's the cost of the support material I suggest you examine ways to reduce the volume of support
RE: How to slice for PETG with PLA supports?
@gnat May I ask the stupid question, why would you want to do that? If it's the cost of the support material I suggest you examine ways to reduce the volume of support
Do what?
Use PLA as supports for PETG? Because PLA and PETG don't like each other much so supports will just pop away with little effort. My experiments with PVA and PLA were terrible both due to how hygroscopic PVA is (which meant I had to pause the print every few hours to run the PVA through my dehydrator for 4-8 hours) and that even with a purge volume of 1000 in each direction (so 2k per tool change) it was still mixed into the actual object and ruined it.
If you are asking about the purge volumes, because (as @antalife pointed out and my experience with PVA showed) when you are doing true multi-material prints you have to do high levels of purging. If you don't then there will be mixing and it will have negative impacts on the structural integrity of the object.
If you are asking about the contrasting colors, it's so that it is easy to tell if the purging is enough or not.
RE: How to slice for PETG with PLA supports?
@gnat May I ask the stupid question, why would you want to do that? If it's the cost of the support material I suggest you examine ways to reduce the volume of support
If you use PETG for the supports, they are nearly impossible to remove. Been struggling with this forever. But with PLA supports they pop right off, and the prints look great.
RE: How to slice for PETG with PLA supports?
I print PLA with PVA supports regularly.
Of course it's been the low-humidity season for several months, but last summer I was doing it as well with no issues.
I have not tried PETg with PLA supports or vice-versa, but I would assume it should work assuming the supports are easily accessible to physically break them away.
RE: How to slice for PETG with PLA supports?
For those interested in PETG with PLA supports, I just discovered a trick that really cuts the print time down, at least for the objects I'm printing which have large areas that need supporting. It occurred to me that the only part that needs to be PLA is the interface! PETG prints fine without supports until the angle gets pretty low, so I set the Support Material: Overhang Threshold to 40, then changed the Multiple Extruders: Support Material/raft/skirt extruder to the primary (PETG) extruder and set the Support material/raft interface extruder to the one with the PLA in it. This knocked over 90 minutes off a 4:41 print! Another print went from 7:08 to 5:20.
Note: I have not run the print yet, but I see no reason why this should not work. We shall see!
RE: How to slice for PETG with PLA supports?
Do what?
The thing thats in the title of your original post
I see your point re. support interface being weak where different materials meet but personally I'd look to tune support values.
RE: How to slice for PETG with PLA supports?
Help me
!
How do you make PLA stick to PETG? When I try PLA supports for PETG objects, I get this. No layer adhesion between them in the wipe tower. The red/orange PETG does not stick to the edges of the wipe tower that are made of blue PLA
My settings: PLA temp 230, PETG 255. Extra loading distance -15, wipe tower bridging 5mm, travel lift enabled.
What am I doing wrong? Thanks!