How about this feature.
When nozzle finishes the perimeter and needs to move away from it (say a sircle) it sometimes moves backwards from drawing direction.
Instead, make it move couple of mm's forward (which ever forward it went) to prevent cutling up.
For example.
Black is the filament
Green is the nozzle path
Red is when path aproachign the end and travels to new location
(NOTE I did not mark travel with a different color, sorry, its all red and shoudl be obvious anyway)
Notice how sharp path changes ? When it does that, it tends to pull some filament off the end causing a gap or even tare it off the bed (depending what you print on)
The proposed part of the picture suggests to add aditional "move over/wipe" (without extrusion, perhaps retraction) over the surface to "seal the deal" before changing perimeter.
It wouldnt be such a big deal if perimeter would finish complitely before changing to another perimeter (if there were more then 1 black lines making up the perimeter) but this feature would still play a role in increasing the quality.
Its more obvious when printing ABS. I see gaps in those areas allover because i print objects with many many inner perimters etc.
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illuminarti 18
I think that slicers and/or firmware could be more intelligent for sure, but I'm not sure that that thing isn't just more or less the same as acceleration, though, contrary to what the blurb on the page says? Perhaps it isn't described as well as it might be.
What is needed, I think, is to decouple the extruder from the x-y motion, so that pressure build up/release is managed. E.g., Finish extruding early on a layer, so the pressure dies down before the z-change or move.
Simplify3D has a concept of this called 'Coasting' which works really well. For instance, in the double-wall cup, shown below, I set the coast distance is just over 2mm, leaving an apparent gap in the wall around the z-scar area. The head passes over that gap, but not actively extruding. The pent up pressure oozes into that gap anyway, so it closes it just fine, and then when the head pauses to change layer, there is less scarring as a result. It's a crude control, but quite effective.
Marlin does have some code in it that is supposed to try to model and manage the hysteresis effects and pressure in the Bowden tube, and compensate for it, but I'm not sure if it actually works - it's not used in the current UM firmware.
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