M207 per extruder (rather than per tool)
deckingman last edited by
I'm probably the only person in the world who would use this, and it may not even be necessary or work, but I thought I'd lob this pebble into the pond and see what ripples come back.
The usage case is for mixing hot ends, specifically the latest iteration of my six input design which has five inputs going through a mixing chamber and a sixth input which has a (almost) direct path to the nozzle). The rationale being that the path through the mixing chamber is both long and complex so retracting those filaments at the input might not necessarily result in a reduction of pressure at the nozzle tip. The sixth filament (which would be clear and thus neutral in colour and only a single digit percentage of the total mix), effectively bypasses the mixing chamber and has a direct path to the nozzle would therefore act as a sort of plunger.
So it may be unnecessary or even undesirable to retract all six filaments by the same amount as is currently the case with a multiple input single tool. Retracting just the one with the direct path might work better. Or more likely retracting the other five by a small amount but the sixth one by a larger amount might be better. It gets a little complicated because of the interaction between distance and feed rate thus affecting the time it would take for each drive to complete the retraction move. My gut feel is that the feed rate should be respected which would mean that there would need to be a slight pause after the shorter retractions for the longer retraction to complete. Alternatively, individual feedrate per drive (as well as distance) might work better.
It's a chicken and egg situation - I can't test if it will work unless it is implemented but conversely if it does get implemented, it might not work any better than the current situation of retracting all filaments by the same amount.
So the request is to add a "D" parameter to M207 so that different retraction settings can be used for individual extruder drives where multiple drives are used on a single tool. I'd be happy enough using multiple M207 commands, rather than trying to cram all those parameters into one single command.
Possible? Doable? If so, what would be the likelihood of it happening and what would be an approximate timescale for it to be implemented?
@deckingman I've added this to the firmware wishlist. It's unlikely to make it in RRF 3.4 because we are now aiming for a quick release cycle, but maybe in 3.5.
deckingman last edited by