2 Extruders 1 Hotend

AS-3D Druck

Hi Guys,

I'am currently design my Y Spiltter to print in 2 Colors eatch Layer without gone stop the entire Print and switch Filament and so on.
https://www.youtube.com/watch?v=a3ttwJHG1a4
This is what i want with 2 Materials but eatch Extruder need a Thermistor right?
So how can i create that "dummy Thermistor"?

And is there something else that i need to change to get this Type of printing to work?
(I know that i have to change my Slicer that shouldn't be a Problem)

dc42

You don't need to create a dummy thermistor. See https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer#Tool_definition_section.

DjDemonD

Yeah you can define tools like this:

; Tool definitions
M563 P0 D0 H1 F0 ; Define tool 0 (extruder)
G10 P0 S0 R0 ; Set tool 0 operating and standby temperatures
;*** If you have a single-nozzle build, comment the next 2 lines
M563 P1 D1 H1 F0 ; Define tool 1 (extruder)
G10 P1 S0 R0 ; Set tool 1 operating and standby temperatures

This makes tool 0 (P0) use the first extruder (D0) and heater 1 (H1) the single hotend, and fan 0 attached to that hotend.
Tool 1 (P1) uses extruder drive 1 (D1) and Heater H1 and Fan 0.

Youll then need tool change scripts to automatically retract one filament and load the other one, see kraegar's post https://www.duet3d.com/forum/thread.php?id=1010 and you will see how this works, and then to be able to slice the model to perform the tool changes at the right point, and prime an amount of filament to get the colour pure before moving back to the print (I haven't got this far yet).

What I am struggling with though is how the firmware handles the tools. So if I have filament loaded into the hotend for tool 1, but the machine powers up with T0 active, how can I change tools to reflect the actual startup conditions, not command a tool change to run (as the right tool is loaded already)?

AS-3D Druck

Thx for you're help Guys.

If you done with you're Print you can rectract the Filament (for me both cause i use only 2) to the Waiting Position a few mm before it gets in to the Y Splitter.
With this little Trick it dosen't matter what Filament is loaded cause you can just choose you're Extruder to print with for the next print without get in to the 1 Filament blocks the other Situation. I hope I have made myself clear. (Just got up)

DjDemonD

Thank you, and yes at first that makes sense, so I could write a separate macro which just retracts the filament after printing. This would leave both filaments just above the splitter. But lets say the machine starts up with T0 selected and I want to print with T1 (or start a print with T1) when I send a T1 (or a T1 is sent in gcode) the machine now retracts the T0 filament right out of the extruder, and loads T1. This is not very satisfactory.

We need a way to set the starting conditions without running the tool change macro.

Or we need to be able to use a conditional statement in the tool change macro which checks the state of which tool is active and skips the tool change.

The issue is despite RRF being incredibly clever in how it handles tools, and versatile - the 2 in 1 out type system especially with a splitter is not specifically catered for.

DjDemonD

So it seems turning the motors off before sending a tool change will achieve this.

dc42

Have you considered removing the T0 in config.g so that the printer starts up with no tool selected? Putting T0 in config.g is just a convenience for users of single-extrusion machines, to save them from having to set up their slicers to generate the T0 command at the start of the print.

DjDemonD

Yes so that is an improvement. If there is no T0 or T1 command in config.g it starts with no tool active.

If I send m84, then T0 or T1 I get a "no-moves" tool change.

I will have to ensure when doing a single colour print that I manually select a tool before loading a gcode to print. Or does it default to T0? Or throw an error "no tool selected"?

One further question about temperatures. If I have active/standby temps defined in config.g then the firmware will set those temps (I know I don't need standby temps as I only have one extruder), on a tool change. If I do not specify them here will the firmware switch temps to 0 on tool changes? I only ask as it would be a pain to have to change these set temps in config.g if I switch from ABS to PLA for example?

(I deleted the other thread - no point duplicating this info).

dc42

When doing multi material prints, you should use G10 commands in the slicer start gcode to set the active and standby temperatures.

DjDemonD

Of course, much obliged.