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Controlling temperature on tool changes  

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Anachronist
(@anachronist)
Estimable Member
Controlling temperature on tool changes

I'm trying to make a multicolor print using PLA and PLA+. The PLA has a working temperature of 210° but the PLA+ jams at that temperature. I cannot print at less than 220° with the PLA+.

This temperature difference creates two problems:

  1. Whenever the MMU2 changes from the PLA+ to the PLA, the temperature drops to 210°, but then the PLA+ remaining in the nozzle to be purged onto the wipe tower jams the nozzle.
  2. On a single-color print, if the previous print job was with that high-temperature PLA+, and I'm trying to print something with regular PLA, the initial purge line temperature is too low and the nozzle jams.

So what I would like make some modification to the slicer gcode to do the following:

  • Always do the pre-print purge at 220° or the filament's first-layer temperature, whichever is higher.
  • When changing tools, purge on the wipe tower at the higher temperature of the current or prior filament.

I have no idea how to do this. Would someone point the way?

I've been manually clearing the nozzle when needed but this is painfully slow. I cannot believe that this isn't a solved problem already.

Posted : 28/03/2022 5:35 pm
BaconFase
(@baconfase)
Eminent Member
gemmagoss
(@gemmagoss)
New Member
RE: Controlling temperature on tool changes

Thanks, very helpful

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Posted : 14/04/2022 3:53 am
Anachronist
(@anachronist)
Estimable Member
Topic starter answered:
RE: Controlling temperature on tool changes

That is helpful. The post-processing script that might do what I need is for Slic3r gcode. I know PrusaSlicer is forked from Slic3r, but I don't know if the gcode generated by PrusaSlicer has diverged. The script hasn't been updated in quite a while on GitHub: https://github.com/workinghard/mmuGcodeParser

You'd think this was a no-brainer for a slicer. Purge temperature should the the higher of the current or next filament working temperature. That's all.

Posted : 14/04/2022 6:35 am
BaconFase
(@baconfase)
Eminent Member
RE: Controlling temperature on tool changes

I mean look at the timestamps. Those posts were even made before the last update to the MMU firmware which itself was back in early 2019. If ever you needed evidence of how the MMU is the red headed stepchild lol. My ridiculous guess is all MMU stuff is done by one person on their lunchbreak sometimes if they feel like it and I doubt there's any more resources put into it these days with the XL on the horizon but I'd be happy to get surprised.

Posted : 15/04/2022 8:28 pm
Anachronist
(@anachronist)
Estimable Member
Topic starter answered:
RE: Controlling temperature on tool changes
Posted by: @baconfase

I mean look at the timestamps. Those posts were even made before the last update to the MMU firmware which itself was back in early 2019.

I noticed that too. However, the MMU firmware doesn't have anything to do with nozzle temperature while purging. All the MMU does is retract a filament and feed a new one into the extruder. The temperature control is determined by PrusaSlicer.

Posted : 15/04/2022 8:36 pm
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