Feature Request: Add option to dwell + reprime between fast layers (alternative to slowing down print speed)

[FIRES-3D]

Version

PrusaSlicer 2.3.3+win64

Operating system type + version

Windows 10 Pro 64-bit

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

Prusa MK3S

Feature Request Description

Add options in "Filament Settings -> Cooling -> Cooling Thresholds" box:

• "Dwell and reprime nozzle between layers if layer print time is below _______ seconds." (Default = 0 / Disabled)
• "Minimum repriming length: ______ mm"

This feature would permit normal print speeds to always be maintained regardless of layer size. After a fast layer is printed, the remaining layer time would be spent with the nozzle dwelling off to the side, then re-priming using a short line, then resuming the next layer.

Note, for best results the repriming feature/geometry should be printed with every single layer even when it's not needed (perhaps print a circle instead of a line/wall to avoid wobble issues with tall prints). It can be quite small so should not be excessively wasteful (and, this option would likely be disabled by default anyway)

Reasoning

Reducing nozzle speed to extend layer times is not a perfect solution in every case. Below are some potential undesirable outcomes:

• Inconsistent surface finish (sheen) due to varying perimeter speeds between layers
• Inconsistent dimensional accuracy due to varying perimeter speeds between layers (can feel tiny "ridge" at each fast/slow layer transition)
• Curling due to very hot nozzle spending extended time in close proximity to freshly-extruded layer (potentially also blocking cooling airstream)
• Inconsistent filament extrusion temperature; i.e., the temperature of the actual filament as it exits the nozzle. Lower print speed = more heating time = higher filament temp (regardless of nominal heatblock temp setting)
• Poor performance on very small layers. For various reasons, a reasonable "min print speed" is desirable, but this means very small layers are unable to be sufficiently cooled.

Adding an option to dwell + reprime nozzle would enable the entire print to be completed (consistently) at the nominal settings, while also providing sufficient cooling time between layers.

Note, this suggestion applies particularly to:

• Fast prints (90+ mm/s), where the difference between nominal print speed and min print speed is very large
• Wide nozzles (0.6mm), for which the larger layers require additional cooling, slow nozzle speeds can increase filament oozing, and filament/heatblock temp differences are accentuated (especially at high print speeds).

[dartrax]

This idea also evolved in #6136.

[bubnikv]

Duplicate of #7177
Closing this one.

[batata004]

@dartrax I think you provided the best solution in all the threads about this subject! Instead of creating a tower, instead of waiting and retracting filament... what about increasing the infill area on layers where the printing time is below a threshold? I think this is awesome cause at least the "extra" filament is being printed on some useful area (instead on a tower). And I think this solution of yours should be pretty easy to implement!