Missing load filament option

Aurimas

@chrishamm great. thank you. I wish someone referred me this earlier

Aurimas

@Aurimas so from what I see it is not possible to use two extruders for a single tool and use load filament function?
if you load filament just for one of them the second one would not be affected and when the retractions need to be done they wouldn't work?
can you please elaborate on this?

chrishamm

@Aurimas That is correct. You can create two (or more) other tools to manage filaments of the other extruders if you have a mixing hotend.

Aurimas

@chrishamm it is not mixing hotend.
I have setup with 2 extruders.
It is a direct drive setup, but I use bowden tube to guide the filament - it is over 2m long run.
to reduce the load on the extruder at the hotend I have another one pushing the filament into the tube - push/pull setup.
because of this I have assigned 2 extruders to a single tool.
so from what you are saying it is not possible to use load filament function in this setup?

gloomyandy

@Aurimas It would probably help if you posted your config.g file so folks can see exactly how you have the tools and extruders configured. Also what does your gcode look like? A small sample showing moves that includes extrusion would help.

Aurimas

@gloomyandy here it is config.g
there is nothing to show as a sample move - two extruder motors have to move in sync.
I am using firmware retraction thus both motors have to comply with the movements

gloomyandy

@Aurimas At line 99 in your config.g you have

M567 P0 E1:1

Which means you are in effect using a mixing hotend (see: https://docs.duet3d.com/en/User_manual/Reference/Gcodes#m567-set-tool-mix-ratios). I understand that in reality you are using two motors to feed a single hotend in a push/pull relationship, but as far as RRF is concerned you have two extruders configured in a mixing arrangement so it will be expecting two separate filament feeds into them.

It may be that there is a better way to configure this sort of setup to get what you want, but it is not something I have any experience of. Others like @deckingman may be able to help? Perhaps just doing something as simple as driving both motors from the same driver would work? Good luck!

deckingman

@gloomyandy @Aurimas
I saw my name mentioned so..... IMO, it ought to be possible to use M701/M702 with a push-pull arrangement but it isn't.

From the notes - quote "This code will work only for tools that have exactly one extruder assigned."

DWC assumes that any tool with more than one extruder must be a mixing tool and does not discriminate between tools which have a mixing ratio that adds up to unity, and those which use 1:1 mixing in a push-pull arrangement.

Of course, there is nothing stopping anyone from using their own macros to load and unload filaments but one cannot use M701/702 when more than one extruder is assigned to a tool.

Alternatively and as @gloomyandy suggested, it might be possible to connect both extruders to the same driver and configure the tool to use that "single" extruder.

Aurimas

@deckingman thanks
connecting to one driver is not an option. it would be like going backwards in evolution - having all the tools in the world and then still using a chisel to dig a cave.
in some cases (an in this case we do) you use 2 different extruders for the feed since you might have high quality extruder on the head and a different one on the feed.
Macro is retty much the only option then, it just would be nice to have real tool - especially for customers to use rather than using workarounds.

thanks guys

deckingman

@Aurimas Slightly off topic, but how are you getting on with your push-pull arrangement? Most people have difficulty getting both extruders perfectly synchronised such that one is not fighting against the other. For short prints, this isn't too difficult but for multi-hour prints, a difference of 0.01% can lead to problems. One user I know of instigated my suggestion that he feeds X amount of filament from the reel into a "loop" and senses when the loop gets depleted before repeating.

Aurimas

@deckingman I cheated a little.
first of all I have bowden setup between the extruders.
it reduces the feed issue, but then on longer prints I have disconnected the tube and observed the behaviour of the filament to tune the steps for the push filament. If the filament length was coming out faster then the real extruder was consuming I reduced the steps obviously.
the second cheat on push extruder lower the current, so that if there is mismatch the extruder will skip steps.

chrishamm

@Aurimas Why don't you simply define your tool with M563 L0 then? If you only have a single hotend with two extruders, that will bring back the filament load/unload option for your tool by telling RRF to map the loaded filament to the first extruder only. I don't see why this wouldn't be possible.

Also note that M567 P0 E1:1 will mess up the filament-based estimation, you should use M567 P0 E0.5:0.5 and double the E steps per mm instead. You may also want to adjust the E acceleration/max speed/jerk accordingly.

Aurimas

@chrishamm does that mean that with L0 both extruders will still work like one? i.e. will do retractions at the same time?

with the ratio - haven't noticed any issues. works just fine

thanks

chrishamm

@Aurimas Yes, that's right, L0 is just a value for filament management.

Aurimas

@chrishamm said in Missing load filament option:

@Aurimas Yes, that's right, L0 is just a value for filament management.

thanks. will try that