Horizontal Scarf Seams rather than vertical #1267

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MrUnknownDE · 2026-04-05T17:08:24+02:00

MrUnknownDE commented

2026-04-05 17:08:24 +02:00

Originally created by @Traq-r on 12/25/2025

Is there an existing issue for this feature request?

I have searched the existing issues

The current scarf seam logic presses the nozzle down through adjacent walls when beginning a scarf on Inner/Outer/Inner or Inner/Outer wall ordering; since my nozzles have a flat that appears to be wider than the nozzle hole (ie. my 0.4mm nozzle appears to have more than 0.4mm flats either side of the opening), this can squash more than one internal wall and the excess material appears to impact seam quality.

Which printers will be beneficial to this feature?

All

Describe the solution you'd like

It occurred to me that if the nozzle were to ramp horizontally from nearly overlapping the inner wall (ie. expose 10% of the nozzle when extruding 10% of the scarf flow) that there would be no squashing of prior walls and the extrusion should flow more cleanly. A brief search online shows me that there is no simple formula for calculating the height (sagitta) of an arc for any specific area, but a series of Goal Seeks in Excel plus a chart with a trendline gave me a formula of:

Offset = NozzleD * (0.835520112 * ScarfPercent) + 0.082239944)

where ScarfPercent steps from 10% to 90% along the seam overlap. This offset would probably have to reference from the centreline of the full extrusion, or possibly treat the line width as the "Nozzle Diameter", or there may be a hybrid calculation that better accounts for both nozzle exposure and requested line widths...

Since the nozzle progressively overlaps the horizontal scarf at the end of the loop, no additional changes should be required to match the new geometry; the extrusion would simply flow differently through the exact same gcode. Again though I realize that if someone were to request a 0.6mm line width from a 0.4mm nozzle, a simple 10% offset width would completely occlude the small nozzle, so there's likely more math required to figure this out.

Describe alternatives you've considered

No response

Additional context

No response

*Originally created by @Traq-r on 12/25/2025* ### Is there an existing issue for this feature request? - [x] I have searched the existing issues ### Is your feature request related to a problem? The current scarf seam logic presses the nozzle down through adjacent walls when beginning a scarf on Inner/Outer/Inner or Inner/Outer wall ordering; since my nozzles have a flat that appears to be wider than the nozzle hole (ie. my 0.4mm nozzle appears to have more than 0.4mm flats either side of the opening), this can squash more than one internal wall and the excess material appears to impact seam quality. ### Which printers will be beneficial to this feature? All ### Describe the solution you'd like It occurred to me that if the nozzle were to ramp horizontally from nearly overlapping the inner wall (ie. expose 10% of the nozzle when extruding 10% of the scarf flow) that there would be no squashing of prior walls and the extrusion should flow more cleanly. A brief search online shows me that there is no simple formula for calculating the height (sagitta) of an arc for any specific area, but a series of Goal Seeks in Excel plus a chart with a trendline gave me a formula of: Offset = NozzleD * (0.835520112 * ScarfPercent) + 0.082239944) where ScarfPercent steps from 10% to 90% along the seam overlap. This offset would probably have to reference from the centreline of the full extrusion, or possibly treat the line width as the "Nozzle Diameter", or there may be a hybrid calculation that better accounts for both nozzle exposure and requested line widths... Since the nozzle progressively overlaps the horizontal scarf at the end of the loop, no additional changes should be required to match the new geometry; the extrusion would simply flow differently through the exact same gcode. Again though I realize that if someone were to request a 0.6mm line width from a 0.4mm nozzle, a simple 10% offset width would completely occlude the small nozzle, so there's likely more math required to figure this out. ### Describe alternatives you've considered _No response_ ### Additional context _No response_

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Reference: github/OrcaSlicer#1267