Filament Swap

[magpul]

After updating to the newest Orca Slicer, I now have a strange issue. At every filament change when the new head is picked up, the head will move forward - pause - extrude filament and then move to the prime tower. This leaves maybe a 5 mm long string of filament (hanging chad) stuck to the side of the prime tower. I checked the retraction section and “Extra length on restart” is set to 0. The machine g-code for filament changes calls out a macro “SM_PRINT_PREEXTRUDE_FILAMENT INDEX=1”. I cannot find this macro anywhere in the fluid dashboard or config files. Im at a loss at this point.

Snapmaker Orca 2.4.1

here is a picture of the back side of the prime tower. the strings are about 5mm long. (I updated my post)

in the printer settings for each tool head I have the “retraction length tool change” set to 5mm not the default 10mm.

[CrazyIvan]

Please be specific: do you mean Snapmaker Orca vs. Orca Slicer, and exactly which version do you mean by “latest”?

[magpul]

Snapmaker Orca 2.4.1

[Zoe_M]

Thanks for the feeback.

I saw another similar feedback here:

Snapmaker Orca V2.4.1 Beta Release

Snapmaker Orca 2.4.1 – Serious printing issues on ALL FIVE of my U1 printers! I have five Snapmaker U1 printers, and ALL FIVE started producing severely damaged multicolor prints after updating to Snapmaker Orca 2.4.1. The toolheads appear to collide with already printed objects when moving to the prime tower. The prime towers are damaged, and the prints are covered in blobs, unwanted filament strands, and other defects. These same models printed perfectly before the update. Photos of the fa…

Did you have this issue on multiple different prints? Can you share me the .3mf file?

The issue has been reported to the senior engineers for confirmation. I’ll update it once there is any improvement.

Best regards.

[magpul]

yes the issue was on multiple different prints. I am currently printing another file, and changed the “retraction length tool change” back to 10mm (default). The problem is still there.

I dont know how to share the 3mf to you. i get an error, file type not allowed.

[magpul]

I ran the problem through Ai, and this is what was found from the exported g-code.

What the g-code shows

Every tool change in your file follows this sequence:

text

T1
SM_PRINT_PREEXTRUDE_FILAMENT INDEX=1   ; macro purges & wipes at clean station
G90
M106 P2 S178 / M106 S255 / M104 S215 T1 ; fan & temp restore
SET_PRESSURE_ADVANCE ADVANCE=0.02
G1 E-2 F3600     ; retract 2mm
G1 Z2.92 F30000  ; descend Z
G1 E2 F1800      ; unretract 2mm  <-- NOZZLE FULLY PRESSURIZED HERE
G1 X42.500 Y141.750 F30000   ; travel to prime tower
G4 S0
; CP TOOLCHANGE WIPE ...    ; tower extrusion starts

The problem: the unretract (G1 E2) is emitted before the travel move to the tower, not after it. So the printer actively pushes 2 mm of filament into a nozzle that’s already at maximum pressure (it was just purged by the macro), and then travels to the tower.

Hope this helps. Im going to try another ai and see if it finds the same result.

[magpul]

another result:

That observation matches the g-code line-for-line and confirms the diagnosis. Here’s what you’re watching:

What you see	What’s executing
Head moves forward	The pre-extrude macro finishing — purge at the clean station, wipe, then the return/park move
Pause	Fan/temp/pressure-advance restore, then G1 E-2 (retract) + G1 Z (descend)
Extrudes	G1 E2 F1800 — the unretract, fired while the head is stationary
Moves to the tower	G1 X42.500 Y141.750 F30000 — the travel, carrying that fresh 2 mm blob plus full purge pressure

So the extrusion you’re seeing is literally the G1 E2 line — the slicer unretracts at a parked head instead of at the tower, and then drags the result across the bed. It’s not ooze, it’s a commanded extrusion in the wrong place. That’s about as clean as a bug diagnosis gets: your print’s behavior, the g-code lines, and the config dump all agree.

For the Snapmaker ticket, include your description verbatim plus this mapping — “head moves forward, pauses, extrudes, then moves to the tower” is exactly the T1 → macro → E-2 → Z → E2 → travel sequence, and it will save their engineers time. The cube g-code plus a photo of the trail is everything they need to reproduce it.

[Zoe_M]

Hi, Thank you very much for the details.

Here’s an update:

• This issue is planned to be fixed in a future Snapmaker Orca update: 2.4.1: tower near the right bed edge, the new head drops to layer height at the dock and crosses the plate · Issue #1168 · Snapmaker/OrcaSlicer · GitHub
• For now, our engineer recommends disabling the “Wall Gap” setting and placing the Prime Tower at the edge of the print bed rather than elsewhere.