Tweak needed for G10/G11 firmware retraction

[deckingman]

As title, the documentation for G10 firmware retraction is a somewhat lacking - or at least I couldn't see the relevant bit. When using a multi input hot end, G10 will retract all filaments associated with a tool, not just the one that may be moving forward. So for example, a tool defined something like M563 P0 D0:1:2 with a mixing ratio of something like M567 P0 E1.00:0:0 will use only extruder 0 when printing, but will retract extruders 0,1 and 2 when a G10 is encountered. Likewise a G11 will un-retract all 3 extruders. So my suggestion would be to add a sentence something like "G10 and G11 will retract and unretract all extruders associated with a tool as defined by M563, regardless of the mixing ratio set in M567". It will just clarify things for those who are "not in the know".

[jay_s_uk]

@deckingman or maybe the firmware needs modifying to respect the mixing ratio?

[deckingman]

@jay_s_uk said in Tweak needed for G10/G11 firmware retraction:

@deckingman or maybe the firmware needs modifying to respect the mixing ratio?

That's something that keeps getting brought up from time to time. The problem is that with something like my own design or a Diamond which have all inputs loaded, if you retract just the filament that is moving forward, then all that happens is that filament is drawn from one of the other inputs, rather than the nozzle tip. So you effectively get no retraction. A mixing ratio of say 50:50:0:0:0:0 will retract drives 0 and 1 equally, but not drives 2,3,4 and 5 so you'd have the same problem. Hence the reason we retract all drives by the same amount, regardless of which filaments are actually moving forward as the print progresses. Which of course can lead to other problems, especially when one of those filaments is soft such as TPU of Polypropylene which is the current battle I'm fighting

[jay_s_uk]

@deckingman ah, that makes sense. I'll withdraw my suggestion

[droftarts]

@deckingman

G10 and G11 will retract and unretract all extruders associated with a tool as defined by M563, regardless of the mixing ratio set in M567

Thanks, I've added a note to G10 and G11 to this affect.

If you need more control over the retraction, one could:

1. Ask @dc42 to add more control to M207, by specifying the retract and unretract distances per extruder of the tool, rather than of the whole tool. eg M207 P1 S0.5:1:0.1:0.1 R0.5:1:0.1:0.1 F2000 where additional values for S and R parameters are given for each extruder. This would give you maximum control over retraction.
2. Ask @dc42 to allow M207 to respect mixing ratios on retraction, maybe with an additional parameter/switch.
3. Use software retraction; a retraction move sent by the slicer should respect the mixing ratios.

I understand that 2 and 3 are not ideal, but does at least give you some control; you could change the mixing ratio before each retract/unretract, and set them back afterwards, probably using a slicer post-processor.

Ian

[deckingman]

@droftarts Good that you've added a note. I don't need any more control. At least I don't think so given that even with a mixing ratio of zero, that filament still needs to be retracted along with all the other loaded filaments. See also my reply to Jay above.