Multimaterial "no sparse layers" will make tool collide printed parts when tool change #1305

New Issue

MrUnknownDE · 2026-04-05T17:16:23+02:00

MrUnknownDE commented

2026-04-05 17:16:23 +02:00

Originally created by @psychotik2k3 on 12/21/2025

Is there an existing issue for this problem?

I have searched the existing issues

OrcaSlicer Version

2.3.1

Operating System (OS)

Windows

OS Version

windows 11

Additional system information

not applicable

Printer

snapmaker U1

How to reproduce

If on a multi tool printer project you check "no sparse layers" to have a minimalist prime tower,
when a tool change is happening, the tool will move over the prime tower position, lower Z to the tower height (which may be lower than printed parts), prime and then will park the tool head without going back to the original Z value.
Because of that the tool head will bump into printed parts and either make a shift on X/Y or unhook the part from the bed.

the culprit code seems to be on src/libslic3r/GCode/WipeTower2.cpp

Actual results

here is an example of the generated code i added somment comments

`;WIPE_END
SET_VELOCITY_LIMIT ACCEL=10000 ACCEL_TO_DECEL=5000
EXCLUDE_OBJECT_END NAME=Catan_Border_Straight_Magnetic.stl_id_8_copy_0
G1 Z7.92 F30000
G1 X13.25 Y234.75 Z7.92
G1 Z7.52 ;=====> z height is 7.52
G1 E.8 F2100
G1 E-.8 F1800
G1 Z.12 F30000 ;=====> z height is 0.12
G1 E.8 F2100
;HEIGHT:0.12
;TYPE:Prime tower
;WIDTH:0.5
;--------------------
; CP TOOLCHANGE START
; toolchange #1
; material : PLA -> PLA
;--------------------
; WIPE_TOWER_START
M220 S100
; CP TOOLCHANGE UNLOAD
;WIDTH:1
G1 X13.750 Y235.250
SET_PRESSURE_ADVANCE ADVANCE=0
G1 F20529
G1 X47.250 E1.6283
G1 Y236.250 F7200
G1 F20529
G1 X37.982 E0.4505
;WIDTH:0.5
G1 Y237.000 F2400
G4 S0
G1 E-10 F1800
; filament end gcode
M104 S70 T1 ; set nozzle temperature ;cooldown
; Change Tool1 -> Tool2 (layer 61) ;=====> z height is still 0.12
G91
G0 Z1.5 F600 ;=====> z height is 0.12+1.5=1.62
G90
G1 F21000

; 61
M109 S220 T2 ;=====> z height is 1.62 parts are more than 7mm tall => collision
T2`

Expected results

here is an example of the generated code

`;WIPE_END
SET_VELOCITY_LIMIT ACCEL=10000 ACCEL_TO_DECEL=5000
EXCLUDE_OBJECT_END NAME=Catan_Border_Straight_Magnetic.stl_id_8_copy_0
G1 Z7.92 F30000
G1 X13.25 Y234.75 Z7.92
G1 Z7.52 ;=====> z height is 7.52
G1 E.8 F2100
G1 E-.8 F1800
G1 Z.12 F30000 ;=====> z height is 0.12
G1 E.8 F2100
;HEIGHT:0.12
;TYPE:Prime tower
;WIDTH:0.5
;--------------------
; CP TOOLCHANGE START
; toolchange #1
; material : PLA -> PLA
;--------------------
; WIPE_TOWER_START
M220 S100
; CP TOOLCHANGE UNLOAD
;WIDTH:1
G1 X13.750 Y235.250
SET_PRESSURE_ADVANCE ADVANCE=0
G1 F20529
G1 X47.250 E1.6283
G1 Y236.250 F7200
G1 F20529
G1 X37.982 E0.4505
;WIDTH:0.5
G1 Y237.000 F2400
G4 S0
G1 E-10 F1800
; filament end gcode
M104 S70 T1 ; set nozzle temperature ;cooldown
G1 Z7.52 ;=====> z height is back to 7.52
; Change Tool1 -> Tool2 (layer 61)
G91
G0 Z1.5 F600 ;=====> z height is 7.52+1.5=9.02
G90
G1 F21000

; 61
M109 S220 T2 ;=====> z height is 9.02 no more collision
T2`

Project file & Debug log uploads

log.zip

catan.zip

Checklist of files to include

Log file
Project file

Anything else?

No response

*Originally created by @psychotik2k3 on 12/21/2025* ### Is there an existing issue for this problem? - [x] I have searched the existing issues ### OrcaSlicer Version 2.3.1 ### Operating System (OS) Windows ### OS Version windows 11 ### Additional system information not applicable ### Printer snapmaker U1 ### How to reproduce If on a multi tool printer project you check "no sparse layers" to have a minimalist prime tower, when a tool change is happening, the tool will move over the prime tower position, lower Z to the tower height (which may be lower than printed parts), prime and then will park the tool head without going back to the original Z value. Because of that the tool head will bump into printed parts and either make a shift on X/Y or unhook the part from the bed. the culprit code seems to be on [src/libslic3r/GCode/WipeTower2.cpp](https://github.com/OrcaSlicer/OrcaSlicer/blob/e32dbd3802169116700d130747e50236d29b42bf/src/libslic3r/GCode/WipeTower2.cpp#L2434) ### Actual results here is an example of the generated code i added somment comments `;WIPE_END SET_VELOCITY_LIMIT ACCEL=10000 ACCEL_TO_DECEL=5000 EXCLUDE_OBJECT_END NAME=Catan_Border_Straight_Magnetic.stl_id_8_copy_0 G1 Z7.92 F30000 G1 X13.25 Y234.75 Z7.92 G1 Z7.52 ;=====> z height is 7.52 G1 E.8 F2100 G1 E-.8 F1800 G1 Z.12 F30000 ;=====> z height is 0.12 G1 E.8 F2100 ;HEIGHT:0.12 ;TYPE:Prime tower ;WIDTH:0.5 ;-------------------- ; CP TOOLCHANGE START ; toolchange #1 ; material : PLA -> PLA ;-------------------- ; WIPE_TOWER_START M220 S100 ; CP TOOLCHANGE UNLOAD ;WIDTH:1 G1 X13.750 Y235.250 SET_PRESSURE_ADVANCE ADVANCE=0 G1 F20529 G1 X47.250 E1.6283 G1 Y236.250 F7200 G1 F20529 G1 X37.982 E0.4505 ;WIDTH:0.5 G1 Y237.000 F2400 G4 S0 G1 E-10 F1800 ; filament end gcode M104 S70 T1 ; set nozzle temperature ;cooldown ; Change Tool1 -> Tool2 (layer 61) ;=====> z height is still 0.12 G91 G0 Z1.5 F600 ;=====> z height is 0.12+1.5=1.62 G90 G1 F21000 ; 61 M109 S220 T2 ;=====> z height is 1.62 parts are more than 7mm tall => collision T2` ### Expected results here is an example of the generated code `;WIPE_END SET_VELOCITY_LIMIT ACCEL=10000 ACCEL_TO_DECEL=5000 EXCLUDE_OBJECT_END NAME=Catan_Border_Straight_Magnetic.stl_id_8_copy_0 G1 Z7.92 F30000 G1 X13.25 Y234.75 Z7.92 G1 Z7.52 ;=====> z height is 7.52 G1 E.8 F2100 G1 E-.8 F1800 G1 Z.12 F30000 ;=====> z height is 0.12 G1 E.8 F2100 ;HEIGHT:0.12 ;TYPE:Prime tower ;WIDTH:0.5 ;-------------------- ; CP TOOLCHANGE START ; toolchange #1 ; material : PLA -> PLA ;-------------------- ; WIPE_TOWER_START M220 S100 ; CP TOOLCHANGE UNLOAD ;WIDTH:1 G1 X13.750 Y235.250 SET_PRESSURE_ADVANCE ADVANCE=0 G1 F20529 G1 X47.250 E1.6283 G1 Y236.250 F7200 G1 F20529 G1 X37.982 E0.4505 ;WIDTH:0.5 G1 Y237.000 F2400 G4 S0 G1 E-10 F1800 ; filament end gcode M104 S70 T1 ; set nozzle temperature ;cooldown **G1 Z7.52** ;=====> z height is back to 7.52 ; Change Tool1 -> Tool2 (layer 61) G91 G0 Z1.5 F600 ;=====> z height is 7.52+1.5=9.02 G90 G1 F21000 ; 61 M109 S220 T2 ;=====> z height is 9.02 no more collision T2` ### Project file & Debug log uploads [log.zip](https://github.com/user-attachments/files/24281767/log.zip) [catan.zip](https://github.com/user-attachments/files/24281769/catan.zip) ### Checklist of files to include - [x] Log file - [x] Project file ### Anything else? _No response_

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Reference: github/OrcaSlicer#1305