Help with 2 in 1 out hotend

westech

Greetings!

I'm coming from Marlin so I'm less familiar with Duet. I'm adding a 2 in 1 out hotend (mixing extruder).

In Printer.config

I've added the second extruder:

M569 P3 S1

Do I need to do anything else to set up the extruder? I remember in Marlin I had to define Mixing extruder, and to make sure Marlin wasn't expecting a second extruder heater and thermistor.

Say I just wanted in my gcode to switch from E0 to E1 that is all that would need to be done to switch from Black to white filament.

Thanks

Max

deckingman

@westech Well you have a number of options but they all involve defining tools.

Option 1 is two separate tools (non mixing) which use the same heater, thermistor, and nozzle but separate extruders.

For that you would use something like :

M563 P0 S"Black" D0 H1; define tool 0 to use extruder 0 and heater 1 with default fan
M563 P1 S"White" D1 H1; define tool 1 to use extruder 1 and heater 1 with default fan

Option 2 define a single tool as mixing using the same heater, thermistor and nozzle.
but with both extruders

M563 P0 S"Mixing" D0:1 H1; Define tool 0 as mixing using both extruders
But then you need to set the mixing ratio using M567
So for example M567 P0 E1:00:0.00; set mixing to ratio to use 100% of the first extruder (extruder 0) and 0% of the second extruder (extruder 1). But if you want to change colour, you'll need to change the mixing ratio.

Option 3 - which is how I would do it. Define 3 tools all as mixing but set the initial mixing ratio for each. So:

M563 P0 S"Black" D0:1 H1; define tool 0 to use extruders 0 and 1 and heater 1 with default fan
M563 P1 S"White" D0:1 H1; define tool 1 to use extruders 0 and 1 and heater 1 with default fan
M563 P2 S"Grey" D0:1 H1; define tool 2 to use extruders 0 and 1 and heater 1 with default fan

Then:

M567 P0 E1:00:0.00 ; define tool 0 to use 100% of extruder 0
M567 P1 E0.00:1.00; define tool 1 to use 100% of extruder 1
M675 P2 E0.50:0.50; define tool 2 to use 50% of both extruders 0 and 1

You could add more tools with fixed mixing ratios or you could simply keep tools 0 and 1 and Black and White respectively and vary the mixing ratio for tool 3 to give you shades of grey (or gray if you speak American rather than English). - Oh and you'll get 100 shades of grey, not 50

You haven't said much about the hot end, but if it's truly capable of mixing, then you'll need to retract all filaments that are loaded, not just the one that's moving forward. For that you use G10/G11 and you tell the slicer to use firmware retraction and it will insert G10/G11 instead of G E-n That's why my suggestion would be to define all tools as mixing. Even if you are only printing say "Black" you need to retract both "Black" and "White" hence both extruders need to be in the tool definition. The retraction amount is independent of the mixing ratio and will be the same for all extruders assigned to a tool. You set it using M207.

Edit 1. You have to assign the drive to an extruder in M584.

e.g. if you have ..............

M569 P3 Sn ;first extruder
M569 P4 Sn; second extruder

.....then you'll need

M584 Xn Yn Zn E3:4

i.e tack the second extruder onto the end of your existing M584 using a colon separator.

Edit2 . One thing that trips people up is extruder numbers vs drive numbers. Extruders are assigned numbers in the order that they are created in M584. So the first extruder is 0 and in the example above it is assigned to driver 3, the second extruder is 1 and uses driver 4. When defining tools, you need to use the extruder number, not the driver number.

westech

@deckingman Thank you. This will be my little project.

I'm going to sneak up on it with simply getting both extruders to work. Then I'll figure out the rest.

All that you mention should reside in config.g, or would they get their own file in sys?

deckingman

@westech All in config.g. You already have one extruder drive and one tool defined in config.g as well as the M584 that you need to modify.