Firmware retraction for single tool in multitool setup?



  • I have a Duet2wifi running in a custom corexy with 4 BMG extruders using firmware retraction in a mixing nozzle setup. I am current using the m207 command to define the g10/g11 however this makes all extruders retract and unretract while print causing a wonderful mess. My question is how would one set this to active tool only?
    Please forgive the category not sure if this belongs here



  • @tcmoore87 If you really have a mixing hot end then you really do need to retract all the filaments, not just the one that is being pushed forward. The reason is that if you only pull one filament back it simply draws molten filament from one or more of the other inputs rather than the nozzle tip. The net result is like printing with no retraction at all.

    What problems are you actually seeing? Can you explain a bit more about the mixing hot end you are using? I'll likely be able to help as I use a Diamond 5 colour with 5 Bondtech BMGs.



  • Let say I am using CYMK for colors and my print uses Cyan as a main body with some small mixes of Yellow and Black here and there in the print well at the end of the print if i pull the filaments for a material change each material will have about 30mm of Cyan similar to what you we just describing if i ran just one extruder retracting at a time.



  • I am using the a M3D Fusion modified to a bowden setup with 4 four bmg extruders and a .5 nozzle running petg at 240. I am unable to get the retractions dialed in using slicer settings and have had a little trouble with the firmware. I am using Prusaslicer for software. I have verified that each extruder is retracting at the same time visually.



  • @tcmoore87 said in Firmware retraction for single tool in multitool setup?:

    Let say I am using CYMK for colors and my print uses Cyan as a main body with some small mixes of Yellow and Black here and there in the print well at the end of the print if i pull the filaments for a material change each material will have about 30mm of Cyan similar to what you we just describing if i ran just one extruder retracting at a time.

    Sorry, I'm still not getting it. You are mixing combining mostly Cyan with small amounts of Yellow and Black. That bit I understand.

    This bit I don't understand " if i pull the filaments for a material change each material will have about 30mm of Cyan similar to what you we just describing if i ran just one extruder retracting at a time." What do you mean by "pull the filaments for a material change". Are you talking about unloading filament? I assumed that when you mentioned firmware retraction, you were talking about "normal" retraction of a couple of mm or so during non-print moves. Is that not what you mean?



  • @tcmoore87 . Going back to your first post, you ask how to set G10 retraction for the active tool. Basically, G10 will retract all filaments that are defined in the mixing ratio for the tool you are using (which is the active tool). Because all of those filaments will have a molten pool in the mixing chamber. If you have you have a tool defined that uses all 4 filaments but are only mixing say 3 of those filaments, then the 4th filament will still be retracted even if it;s mixing proportion is set to zero. So to retract only those 3 filaments, you simple define a tool to only use those 3 rather than all 4. Does that answer your question?



  • Yes unloading filament I find that at the end of each filament what ever color I used mainly has attached itself and back fed about 30mm. And Yes for normal retractions using g10/g11 that had been set using m207.



  • @tcmoore87 . Finally, I think you are confusing tools with extruders. A tool consists of one or more heaters and one or more extruders. Pease explain (or post your config.g) how you are defining your tool(s).



  • @tcmoore87 said in Firmware retraction for single tool in multitool setup?:

    Yes unloading filament I find that at the end of each filament what ever color I used mainly has attached itself and back fed about 30mm. And Yes for normal retractions using g10/g11 that had been set using m207.

    Ahhh, now I understand. Basically one or more filaments is back feeding into one or more of the other inputs and you assume this is caused by the firmware retraction yes?



  • @deckingman Yes prior to the firmware retraction i did not have this issue



  • So that being said I cannot "uncouple" the extruders from the tool while mixing for the purpose of retraction and would need to use each extruder as a separate tool and thus would change my mind about this setup and may go back to the 4 separate nozzle I had before. @deckingman Thank you for your help so if I confused you with what i was asking.



  • @tcmoore87 OK. Well the only way filament can back feed into another input is if there is a void in that input. Under normal circumstances, there should be no void because all inputs should contain filament. The only way I can think of that a void could be created is if filament was being retracted when the G10 happens but somehow not un-retracting when the G11 happens.

    One possible reason for that could be if you have set a negative "R" value in in your M207 so that you retract say 4mm but only un-retract say 2mm. Each successive retract/un-retract cycle would leave a 2mm void into which filament from the "main" input gets pushed.

    If you don't have a negative "R" value, then look for something mechanical that could cause the same thing to happen. i.e. a slipping extruder or skipping motor that copes OK with the retract move but struggles to make the un-retract happen fully. A loose Bowden tube coupling might do it too. Or maybe something inside the quad but I'm not familiar with the internals of that.



  • @tcmoore87 said in Firmware retraction for single tool in multitool setup?:

    So that being said I cannot "uncouple" the extruders from the tool while mixing for the purpose of retraction and would need to use each extruder as a separate tool and thus would change my mind about this setup and may go back to the 4 separate nozzle I had before. @deckingman Thank you for your help so if I confused you with what i was asking.

    Read my post above because I might have an answer. But "normal" slicer retraction should only retract one filament (although it's a long time since I used it).


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