[2.6.0 alpha 5 / macos] Tool change happens at current print location, not at the wipe tower location

[themelle]

Description of the bug

When doing multi-extrusion prints using a wipe tower the process for tool changes (in version 2.5.0) was as follows: (let's assume we're using T0 and T1)

• print with T0
• travel to wipe tower location
• change tool to T1
• wipe/purge
• print with T1
• travel to wipe tower location
• change tool to T0
• wipe/purge
• repeat ...

As of version 2.6.0 alpha 5 (and presumably also in the earlier alphas) the tool change process has changed for the worse:

• print with T0
• change tool to T1
• travel to wipe tower location
• wipe/purge
• print with T1
• change tool to T0
• travel to wipe tower location
• wipe/purge
• repeat ...

This effectively ruins my prints as the tool change leaves purge debris and overheat dents on the print.

Please see attached project and resulting code files as well as a screenshot of comparing the gcode at the location of the problem.

Project file & How to reproduce

version 2.5.0 --- ps-250.zip version 2.6.0 alpha 5 --- ps-260a5.zip

Checklist of files included above

• [X] Project file
• [X] Screenshot

Version of PrusaSlicer

2.6.0-alpha5+MacOS-x64

Operating system

macOS 13.0

Printer model

custom delta

[themelle]

It's been almost 2 months since submitting this issue. As it is a bug that makes multi-extrusion unusable (at least for my setup, probably also for others) I at least expected some feedback.

I just don't want this to be pushed down the drain unnoticed 😉

Thanks for your time 🙏🏻

[themelle]

Possibly related to #2672

[kubispe1]

Hi @themelle,

Possibly related to #2672

That's different topic. Never mind.

---

To your issue. We changed this behavior to reduce travel to the Wipe tower where only tool change is performed. So the tool goes directly to the dock or is changed upon the object. It could create a string and make this kind of problem.

ps-270_a1.zip There I made some changes to your 3mf. Use PS270a1 to slice it and you can try to print it. I am quite interested of your feedback. There is a list of changes:

• For both filaments, I switched on Ramming for multi extruders >> will solve your problem

then I made tinny improvements:

• set wipe_tower_cone_angle =30 >> make your wipe tower more stable
• set wipe_tower_extruder =2 >> Using PETG for the perimeter of the tower, will make your tower more compact due to the material.

[themelle]

Dear @kubispe1 ,

thanks for your time and your input - I really appreciate that!

Checking "Enable ramming for multitool setups" indeed did change the game a lot; tool changes are now being performed at the wipe tower again - so that's fixed. Though I did not use your .3mf file, but installed 2.7a1 and changed my filament profiles accordingly.

What puzzles me is that the print looks ugly at places and clean at others.

Specifically, the print looks good for layers without a tool change (see chest and hat), but oddly unclean for layers where tool changes were included (feet, face). From observing the print it seems that speeds were nominal at the single tool layers, whereas the printing speed was substantially higher for layers containing tool changes. Do you have any idea where this may stem from?

Please find the project file attached. smurf sit 1.3mf.zip

Thanks again, Andreas

[themelle]

Dear @kubispe1 ,

are there any news on this issue?

Thanks in advance! Andreas