Wipe Tower - IDEX - Tool change retracts and unretracts on same tool

[soneshp]

Version

2.2.0 up to 2.3.0 beta

Operating system type + version

Windows 10

3D printer brand / version + firmware version (if known)

IDEX - SKR Pro - Marlin 2

Behavior

With relative E distances enabled, using a wipe tower, the active tool is retracting before the tool change, moves to wipe tower, and unretracts. THEN changes tool:

G1 X93.069 Y119.888 E0.38905 ; infill
**G1 E-50.00000 F2400.00000 ; retract for toolchange
G1 X96.734 Y85.147 F6000.000 ; Travel to a Wipe Tower
G1 E50.10000 F2400.00000 ; unretract**
;HEIGHT:0.100000
;TYPE:Wipe tower
;--------------------
; CP TOOLCHANGE START
; toolchange #3
; material : PLA -> PLA
;--------------------
M220 B
M220 S100
; CP TOOLCHANGE UNLOAD
G1  X96.234 Y84.897  
M900 K0
G1 F2000
G1  Y84.397  F2400
G4 S0
; Filament-specific end gcode 
;END gcode for filament

**T1 ; change extruder**

G1  X96.234 Y84.397  
; Filament gcode

G4 S0
G1  Y84.897 
; CP TOOLCHANGE WIPE
G1  X77.234  E0.3780 F1600

---

Disabling Wipe tower causes expected behavior:

G1 X87.649 Y111.231 E0.02201 ; infill
**G1 E-50.00000 F2400.00000 ; retract for toolchange**
; Filament-specific end gcode 
;END gcode for filament
**T1 ; change extruder**
; Filament gcode
G1 X85.572 Y108.116 F6000.000 ; move to first perimeter point
**G1 E50.10000 F2400.00000 ; unretract**
;TYPE:Perimeter
G1 F1200.000
G1 X85.846 Y107.881 E0.00644 ; perimeter

[bubnikv]

The deretraction of the active tool head is a remnant of the single-extruder-multi-material origin of the wipe tower implementation.
@lukasmatena Please help with that, thanks.

[Hades32]

Just found this, too, in the 2.3 RC2:

	Line 12063: T1 ; change extruder
	Line 12107: G1 E-2.00000 F2400.000 ; retract
	Line 12109: G1 E2.00000 F2400.000 ; unretract
	Line 12156: G1 E-2.00000 F2400.000 ; retract
	Line 12158: G1 E2.00000 F2400.000 ; unretract
	Line 12288: G1 E-100.00000 F2400.000 ; retract for toolchange
	Line 12292: G1 E100.00000 F2400.000 ; unretract
	Line 12357: T0 ; change extruder

Is there any workaround?

BTW, why is the wipe tower not supported without relative addressing?

[Hades32]

Working around with a simple regex:

BUT, you must also disable "prime all printing extruders" as there is NO RETRACTION on extruder change...

[Hades32]

Another update: Also when printing without a wipe tower (but still with multimaterial single extruder setup), the slicer seems to ignore the initial "parking position" of the materials. I.e. there is NO unretraction when switching to a material for the first time (although it's of course in the parking position from the last print) but for subsequent toolchanges the unretraction is added correctly.

Should I open a new issue for this?

[giPeteR]

One solution that works quite well is to add a few lines of Custom G-code in the Filament settings.
I have a dual extruder with Marlin. The script is only active when using the Wipe Tower.
You can strip all comments, they just help me find the sections in the G-code. I have plenty of custom scripts.

UPDATE 10/2:
Actually it works better to set set retraction to zero and have a manual length in the filament scripts, here 4mm.

I'm not 100% sure if G92 adds value, though.

Filament Start G-code:

; -------------------------------------->>>
; Custom G-code: Filament ABS - Start - START
; T[current_extruder] ; Current extruder
{if wipe_tower}
; Wipe Tower used. Do extra de-retract.
G92 E0 ; Zero extruders
G1 E{4 + retract_restart_extra_toolchange[current_extruder]} F{60 * deretract_speed[current_extruder]} ; De-retract for toolchange, 4mm.
{endif}
; Custom G-code: Filament ABS - Start - END
; <<<--------------------------------------

Filament End G-code:

; -------------------------------------->>>
; Custom G-code: Filament ABS - End - START
; T[current_extruder] ; Current extruder
{if wipe_tower}
; Wipe Tower used. Do extra retract.
G92 E0 ; Zero extruders
G1 E-4 F{60 * retract_speed[current_extruder]} ; Retract for toolchange, 4mm.
{endif}
; Custom G-code: Filament ABS - End - END
; <<<--------------------------------------

I also have a post processing python script that adds an extra purge the first time the second tool is activated. That's because initially I couldn't get the wipe tower to work. So if a print started with one tool the inactive tool was retracted a lot to prevent dripping, but then needed extra purge when starting.
Purge in front of the table didn't work since I have clips there to hold the bed.

[klack]

Hello, I have created an easy to use post-processing script as a work around for this issue. You can find it here:
https://gist.github.com/klack/915c5d86b6202fcb08af396ad3014fc9

[lukasmatena]

This should be fixed in 2.6.0-alpha2. Feedback appreciated. Closing.