MMU Single-Mode changing between PETG and PLA  

Re: MMU Single-Mode changing between PETG and PLA

Possibly. What I do is remove the MUX, heat up to 250 and push a length of PLA straight through (about 20 cm). You'll feel a bit of extra resistance initially. When done, pull the rest out quickly so it doesn't clog in the heatbreak. I generally do this when changing back to PLA, for swaps between other materials (PET, ABS, Nylon, Flex) I haven't found it necessary.

Re: MMU Single-Mode changing between PETG and PLA

I've tried printing with materials with different temperature settings (PLA and ColorFabb XT) and every of those prints failed eventually.

When the switch is made to a lower temperature material, the nozzle temperature is changed when the head moves towards the wipe tower. Since things cool down pretty fast, the bit of printing that occurs to empty out the nozzle leaves behind material that is too cool already on every change.

Usually the print was underway for about half an hour before this problem starts occurring but when it does, it fails.

I don't think there's anything that can be done about it, the correct way to change temperatures would be to keep the nozzle at the higher temperature until the "head clearing" movement is done and only then allow it to drop to the temperature for the other material, but that's a code change.

I've given up trying to mix 2 different temperature filaments for now.
My MM performs flawlessly (albeit UBER slow due to those lengthy color changes) for the rest of the time.

Re: MMU Single-Mode changing between PETG and PLA

I don't think mixing different temp materials is what he meant. In principle it should be possible to mix temps, but I see many practical issues.
As you said, filament will stick to the nozzle walls and reduce the inner diameter until it clogs.
Actually I don't see that many applications for this scenario anyway, except flex+PLA (for grips and surfaces) or Nylon+PLA (for hinges and other functional parts plus eye candy). And then there's also the question of adhesion.

Re: MMU Single-Mode changing between PETG and PLA

I tried once PVA (as support) and PETG. Just no go with these, because temperature difference between these is too big and
PVA gets too sticky and don't want to extrude after PETG. HIPS works far better in this situation.

--Hannu

Re: MMU Single-Mode changing between PETG and PLA

I constantly mix materials here without issues in single material prints, using the MMU.

Current setup:
Extruder 1: empty
Extruder 2: PLA
Extruder 3: PETG
Extruder 4: XT

I just choose what extruder to use in slic3r for my current object and print. No need to purge/clean/cold pull/....

works just fine.

Re: MMU Single-Mode changing between PETG and PLA

With the standard nozzle? Wow. Couldn't do that with mine. XT prints way too hot. I have some PETG that can be printed at 230, and could mix that with PLA and ABS (but ABS+PETG didn't stick together and PLA+ABS blocks up).

Re: MMU Single-Mode changing between PETG and PLA

Please tell us more specific way what filaments you are using

Re: MMU Single-Mode changing between PETG and PLA

I've noticed when I change from PETG to PLA, using the same extruder....


I constantly mix materials here without issues in single material prints, using the MMU.

Perhaps a reset is due here. I believe the OP was having a problem switching materials between prints from PETG to PLA in the same extruder which makes sense if there is any PETG filament left in the extruder and PLA's lower print temp. The OP was not mixing materials in a single print.

joris.m noted having different materials preloaded in different extruders I assume for convenience. Again, for single material prints. Not mixing.

To the OP, what nils.t suggested is what I do as well. If the PETG unloads fully and allows for the PLA to be loaded and then you get your clicking situation just follow what they posted to clean it out.

Hope this helps or maybe it is me that is off 🙄

Re: MMU Single-Mode changing between PETG and PLA

I run a cleaning filament through my extruder when I change filament types (which I do on my MMU when printing single mode).

I think I have the eSUN version.

I run it through at a bit higher a temp than the last filament used. The extruded stuff has some of that color in it, so I think it has cleaned it out, and I stopped having clogging issues after doing this routinely.

Particularly if any of the higher temp material is in the extruder when you print the lower temp one, it is likely to clog.

A small spool of that cleaning filament lasts forever and i not expensive.

https://www.amazon.com/CLEANING-Filament-Makerbot-MakerGear-Printers/dp/B00MVIYNFW/ref=sr_1_2_sspa?ie=UTF8&qid=1519869014&sr=8-2-spons&keywords=cleaning+filament&psc=1

Re: MMU Single-Mode changing between PETG and PLA

joris.m noted having different materials preloaded in different extruders I assume for convenience. Again, for single material prints. Not mixing.

Exactly