My Solution to Many Dual Extruder Color Changes at Heights

[rifraf650]

So, this tip is in response to having had a few issues that I would consider bugs in S3d. When trying to make color changes by adding a difference process to start/stop at different heights, I ran into issues related to:

- Ooze shield and prime pillar do not print with processes that start at height > 0
- Prime pillar prints at the end of layer, not at the start of a layer

So, I first tried the multiple process approach, so I could cool down my extruder not being used, so it would not ooze. This just never worked well. The biggest problem was proper priming. So, the next approach was to use the {REPLACE} capability to make tool changes at specific layer heights. This worked but since the prime pilar prints AFTER the layer, I cant used it to prime the extruder after a tool change. My solution includes a custom prime pillar in the layer script . The advantage to this approach is you only need a single process (both extruders), and you can make LOTS of color changes easily:

In the Layer Script. This code will make a rectangular pillar to prime the extruder on each layer.

Code: Select all

; custom prime pillar - Change X Y values on first line to be near your part
; make sure retract and advance matches extruder settings 
; extrude amounts set for 0.2mm layer height. Adjust if necessary. 

G1 X-50 Y30 F9000; Change X Position to keep near your part
G1 E2.0000 F1800
G91; switch to relative mode
G1 Y-60 E2.0 F3000 ;
G1 X-2.5 E0.0825 F3000;
G1 Y60 E2.0 F3000 ;
G1 X2.5 E0.0825 F3000 ;
G90; switch to absolute mode
G1 E-2.0000 F1800

In "Additional Commands for Post Processing", each replace line will:
- Retract 10mm
- Change the tool
- Advance 10mm of the new tool

Code: Select all

{REPLACE "\n; layer 5," "\nG1 E-10.0000 F1800\nM135 T1 ; Load extruder 1 offsets\nG1 E10.0000 F1800\n; layer 5, "}
{REPLACE "\n; layer 10," "\nG1 E-10.0000 F1800\nM135 T0 ; Load extruder 0 offsets\nG1 E10.0000 F1800\n; layer 10, "}
{REPLACE "\n; layer 15," "\nG1 E-10.0000 F1800\nM135 T1 ; Load extruder 1 offsets\nG1 E10.0000 F1800\n; layer 15, "}
{REPLACE "\n; layer 20," "\nG1 E-10.0000 F1800\nM135 T0 ; Load extruder 0 offsets\nG1 E10.0000 F1800\n; layer 20, "}
{REPLACE "\n; layer 25," "\nG1 E-10.0000 F1800\nM135 T1 ; Load extruder 1 offsets\nG1 E10.0000 F1800\n; layer 25, "}
{REPLACE "\n; layer 30," "\nG1 E-10.0000 F1800\nM135 T0 ; Load extruder 0 offsets\nG1 E10.0000 F1800\n; layer 30, "}
{REPLACE "\n; layer 35," "\nG1 E-10.0000 F1800\nM135 T1 ; Load extruder 1 offsets\nG1 E10.0000 F1800\n; layer 35, "}
.
.
.

NOTE: Prepare to print will not show the tool changes. You need to Write the GCode, then use File--> GCode Preview to see it. (Example attached)

I've written a simple Excel sheet to set the layer count and automatically generate the REPLACE commands. You may want to prepare to print initially to figure out which layers you want to make changes at, and build the lines manually. It takes a little time, but the results so far are not too bad. I am still using an ooze shield, and combined with the prime pillar, things are coming out fairly clean (minimal ooze on the model). If you wanted, you could add temperature changes and stabilize commands to cool down extruders. If so, I'd recommend moving the head away from your part as the extruders will ooze while heating up.

Gcode preview of color changes at height

Along with this post, I request S3D consider the following bug fixes and features:
- Fix ooze shield and prime pillar to print on processes that start at height > 0
- print the prime pillar BEFORE the layer, not after
- add layer numbers to g-code comments for ; inner perimeter, ; outer perimeter, ; infill, etc... Add better scripting options for REPLACE commands
- Add a tool change at height capability - this could be just like the extruder temperature at layer interface, that allows multiple entries. Bells and whistles could also include a pre-loading of the table with an option of "every x mm", and even consider changing temperature setting and stabilization after a tool change.

[rifraf650]

A couple of examples of how I used this technique.