PETG and PLA filaments (I do not dry them after unbox): Extrdur.com PETG and Extrudr.com PLA NX2

1. PETG:

Bed Temp: 70 celcius

First Layer: 220

Other Layers: 220

2. PLA:

Bed Temp: 70 celcius

First Layer: 200 c

Other: 200 c

What plate do I use?: Satin Coated with 3D Lack to improve adhesion:

https://www.amazon.de/Spr%C3%BChkleber-perfekte-Haftung-Drucker-Druckbett/dp/B01HQ4KXZ4/ref=sr_1_2_pp?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=3RCHO2CNBLBG2&dib=eyJ2IjoiMSJ9.PX61EiMjIi2AAAlmxfhz3xLwjfffBFOMQCOCWjYvB5HkuzPzCgd0-e7g_XACVPQ7HYTt0cjuGJinSxZ8nPOSkz787YGLiumNM19-_MesKnQHkq_jUsEXVon7ch4YFi-PMLyoK7tN5efNUlxQ8I9UqX1dDyGEZ-bcUo4vpZg8Oa2luOG_vNLf58eigpsB-WSV7hhhKQY-F023aocz8wcmTbhPySITcrBtbfcrK4GeIDiG2K0sMPYZlc8EykAIp8xwq9HQfT6HKFt7tGaYkrJSqPnYSPpzC1GF7QWNhtIsfVw.ccGiOzI6NNl6I8zy0DfdZxMRfwq_a6mMsYQSYriFJww&dib_tag=se&keywords=3d+druck+lack&qid=1717009609&sprefix=3d+druck+lack%2Caps%2C90&sr=8-2

I have 0 problems with stringing or adhesion on the satin coated plate, since I started to use the 3D spray above.

What was the key point for me to get good results?

- I have used a trummeter to measure the belts and adjusted them. They were extremley uneven and since I did that, my prints improved. Also one thing to consider: Once you adjust your belt tensions of the prusa XL, you need to run a full calibration again. People forget about that and only adjust the belts, without running the calibration again.

I hope that helps.

I've been testing and have seen some improvements.

I've increased purge volume in mk4/MMU3 from default (80) to 100 and then to 120. I'm using white and black PETG with a red PLA interface only support.

The black causes streaking in the white (light grey). The supports work well. The wipe tower still has a lot of issues with clumping, layer adhesion, etc. This causes print failure eventually, either by layer shift or because globs of material break a support.

I tested lower speeds for the support material (100 down from 120 default) and support interface (40 down from 50 default), and that greatly improved the situation. I'm still testing this, but perhaps I can fix this using another way.

I also lowered the MVS -Max Volumetric Speed on my PLA support material from 15 (default) down to 10mm(3)/s.

Happy printing!

Setting the support extruder to 0 (zero) makes the interlacing happen. Setting it to the specific main extruder resolves.

Based on your description of the error, I come to the following considerations:- Too much heat in either material.- Too little flushing volume with PLA- Too much cooling when printing PLA- Wrong PLA (PLA+?)- Too high printing speed with PLA

PLA sticks to PETG, it just depends on the circumstances.

If you print models with longer supported areas, does PLA adhere equally poorly everywhere? Or are there areas where it sticks better, especially towards the end?

If I have pure PLA supports from the build surface and PETG on top, it works, but only for lower height prints. Anything too high, and things start stringing and getting weird. Perhaps with some beefier supports and a skirt it might improve.

At least the MK3 makes it to the new temperature in time. Since both are based primarily on the same mechanics and the MMU3 is also the same, I would be surprised if the MK4 changed the filament significantly faster or took longer to heat.

So I continued searching and finally found what I was looking for when it came to purging volume. This seems to have the biggest impact of all the setting options! By default, the profiles of the MK4 work with smaller flushing volumes but more pressure, which may be why the problem was primarily noticed there. If you have problems with your print, increase the purging volume (sometimes massively) and you will see how the problems disappears.

This also means that (too) hot PLA is no longer needed; you can leave the temperatures at the optimal values!

I'm currently working on a tutorial and a test file on this topic. I'll let you know here when I'm done with it.