Single Nozzle Multiple Extruders

[Justpass]

First of all, I've done some research to find a good starting script and/or mods to Marlin to accommodate but couldn't seem to find a good one. CMiIW

I am using two extruder aligned to allow switching via a single nozzle, much like Prometheus Bowden combiner. Both filaments are inserted close to the neck of the combiner. Thus, every 'tool change' requires retracting the filament as far as the distance from the nozzle to the neck of the combiner.

Tool Change Script :
G1 E-115 F4500 ; retract far to the neck
G92 E-115 ; the filament is 115mm behind nozzle


The problem only appears at the first layer where the Machine Profile works as a dual nozzle machine.. Generated Gcode will prime any first extruder that goes into action and retract far back to the neck to switch filaments, but I haven't figured out how to prime/extrude the second extruder as far as 115mm (first layer only) down to the nozzle because S3D 'thinks' it is already there!

I know this behavior is completely predictable, as I AM using a dual nozzle profile.

My attempt at this was inserting some logic in the Starting Script :

M82; set to absolute mode
G28; home all axes
G29;
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
G92 E0 ;zero the extruded length


{IF NEWTOOL=1} T1; if print starts with Tool 1
{IF NEWTOOL=1} G1 X0.255 Y0.255 F6000;
{IF NEWTOOL=1} G1 Z0.225 F1002;
{IF NEWTOOL=1} G92 E-115 ; filament is 115mm behind
{IF NEWTOOL=1} G1 E0.0000 F1080 T1; get filament to the nozzle
{IF NEWTOOL=1} G1 X149.745 Y0.255 E7.9242 F3000; start drawing a square to prime
{IF NEWTOOL=1} G1 X149.745 Y149.745 E15.8484;
{IF NEWTOOL=1} G1 X0.255 Y149.745 E23.7727;
{IF NEWTOOL=1} G1 X0.255 Y0.255 E31.6969; square finished

{IF NEWTOOL=0}T0; if print starts with Tool 0
{IF NEWTOOL=0}G1 X0.255 Y0.255 F6000 ;
{IF NEWTOOL=0}G1 Z0.225 F1002;
{IF NEWTOOL=0}G92 E-110 ;
{IF NEWTOOL=0}G1 E0.0000 F1080 T0;
{IF NEWTOOL=0}G1 X149.745 Y0.255 E7.9242 F3000;
{IF NEWTOOL=0}G1 X149.745 Y149.745 E15.8484;
{IF NEWTOOL=0}G1 X0.255 Y149.745 E23.7727;
{IF NEWTOOL=0}G1 X0.255 Y0.255 E31.6969;


M73 P0;
M117 Printing...;


Has anyone figured this out yet?


Cheers

[bbinnard]

I have done some experimenting with dual extruder/single nozzle 2-color printing and I have not had to use any custom GCode at all. The S3D FFF Settings/Advanced/Tool Change Retraction settings handled everything just fine.

After using the Dual Extrusion Wizard to load the 2 parts of my test piece (I used the Thingiverse Traffic Cone) I simply set Tool Change Retraction Distance = 60 mm and Tool Change Retraction Speed = 100mm/sec. After that I simply sliced & printed as usual.

[Justpass]

I have done some experimenting with dual extruder/single nozzle 2-color printing and I have not had to use any custom GCode at all. The S3D FFF Settings/Advanced/Tool Change Retraction settings handled everything just fine.

After using the Dual Extrusion Wizard to load the 2 parts of my test piece (I used the Thingiverse Traffic Cone) I simply set Tool Change Retraction Distance = 60 mm and Tool Change Retraction Speed = 100mm/sec. After that I simply sliced & printed as usual.

bbinnard, don't you have one filament (either) still behind when the very first tool change happen?

[bbinnard]

I don't completely understand your question, but preparing the printer for the first tool change does require pre-loading filament from both extruders into the Y connector. I found that when S3D starts a print it expects the hotend to be fully loaded with filament from Extruder 0. So what I did was to get the hotend up to temperature and manually feed a little filament from Extruder 1 through the hotend. Then I manually backed this out a bit and did the same for Extruder 0. This seemed to get the printer properly set up for the initial print from Extruder 0 and also made it OK to do the first switch to Extruder 1.

[Justpass]

bbinnard,

Exactly, s3d doesn't execute or allow preloading the y combiner for the first tool change.
I could only go as far as unloading old tool, but cannot preload new tool. This is what I use in tool change script :

*y combiner length is 120mm

T[old_tool]
G1 E-120 F4500

T[new_tool]
G92 E-120

[paboman]

Hi,
im having the same problem only on the first layer when the second filament is behind the Y junction.
S3D thinks is in the nozzle already and start to use the second extruder without feeding 60mm of filament into the nozzle, why?
how did you solved ?

[lensfort]

Did anyone solve this?