Dual extrusion best practices?

Tinino

Just curious, I've noticed when I slice a multi-extruder gcode file, that when my duet runs the print and goes to switch tools, it stops heating. If I set my standby temp to 235 (Both filament lines/extruders share a single nozzle) will that resolve the issue of losing the heat when it switches tools? I'm testing that out now, but I'm also curious to see how any of you may have your setups done, just to compare it to what I have.

Currently I just have my 2 tools, both are assigned to heater 1, and then tool 1 is assigned extruder 0, tool 2 extruder 1. I've just now set my standby temps to 235 and my extrusion temps to 235. Looking forward to your replies. Thank you

dc42

Usual practice is to set the standby temperatures to about 40 or 50C lower than printing temperatures, to prevent oozing. That's what the standby temperatures are for.

T3P3Tony

Hi Tinino. By the sounds of it you are using a cyclops style hotend with two in, one out and a single heater? if that is the case then you obviously don't need to cool down between tool changes.

Check your tool change gcode files:
https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer#Tool_change_files

To ensure they are not causing the temperature to change.

Also check your slicer settings as many slicers (especially cura) hide the tool change temperature changes deep in the settings.

dc42

I didn't spot that you are using a single heater for both tools. So I am puzzled that the heater turns off when you switch them, assuming you have set the active temperature for both tools.

Tinino

Hey thanks for the quick responses guys :), I do believe it's the gcode file that Cura is generating, I'll have to look into the settings a bit more and find out where it's stopping the heating. This is my first attempt at a multi-filament setup so there's certainly a learning curve here. Thank you both for the great info. And yes, I do have the cyclops style setup.

deckingman

With my 3 and 5 colour Diamond hot ends, I always define the active and standby temperatures in the start gcode. There are probably other ways of doing it but this is something I set up a long a time ago and it fixed a lot of issues that I was having at that time so I've stuck with it.

So for example I'd have something like this (but this is for 4 tools):
G10 P0 S195 R195 ; Set tool 0 operating and standby temperatures
G10 P1 S195 R195 ; Set tool 1 operating and standby temperatures
G10 P2 S195 R195 ; Set tool 2 operating and standby temperatures
G10 P3 S195 R195 ; Set tool 3 operating and standby temperatures

Then at the end, I always turn them off by putting the following in the end gcode

G10 P0 S-273 R-273 ; Set tool 0 operating and standby temperatures
G10 P1 S-273 R-273 ; Set tool 1 operating and standby temperatures
G10 P2 S-273 R-273 ; Set tool 2 operating and standby temperatures
G10 P3 S-273 R-273

I use Slic3r rather than Cura. In earlier versions this meant having to use different printer settings for each filament as there was only one place to enter these gcodes. Later Prusa versions of Slic3r allow users to put custom gcodes in the "Filaments" section. It doesn't matter how it's done, as long as the commands get inserted before the print proper begins.

IMO it's generally best practice for any changes you make in the start gcode, to be reverted back to default settings in the end gcode. This will ensure that you don't carry over print specific settings to another print job.
HTH