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Ultimaker / Cura

3D printer / slicing GUI built on top of the Uranium framework
GNU Lesser General Public License v3.0
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Acceleration after retraction prime #3351

Open vvranjek opened 6 years ago

vvranjek commented 6 years ago

I print a lot of precise single-walled objects with relatively high speeds. The only problem I have is under extrusion after a move with a retract. Extra prime distance is not an ideal solution for me at all and slowing down print speeds increases printing time immensely.

I believe that accelerating slowly after priming on retraction will completely fix the issue.

I appreciate your good work and hope to see this feature in the future.

smartavionics commented 6 years ago

Of course, the problem is really more than just underextrusion at the start of a wall following a retract/move/prime. Any time the extrusion rate changes suddenly will cause either under or over extrusion. Some printers attempt to compensate for these changes (i.e. the RepRep pressure advance feature) but maybe the slicer could help here.

I have been working on settings for improving cura's bridging capability recently and have come across the opposite problem to you, which is before the bridge starts, it needs to stop extruding far enough away so that by the time the nozzle reaches the start of the bridge, the pressure in the nozzle has fallen so that when the nozzle goes "over the edge" the plastic doesn't just squirt way down.

I'll do some thinking about your request.

BagelOrb commented 6 years ago

Introducing such accelerations might solve that problem, but influence totally different parts of the printing process, which makes it difficult to get control over the process and ensure a given print quality.

Ghostkeeper commented 6 years ago

This sort of compensation gets into the realm of predictive modelling the flow of material, which can be done with some sort of compensations here and there but in general is a bit beyond the scope of what a slicer can achieve right now...

Mulakulu commented 2 weeks ago

I had the exact same idea as you vvranjek, just 6 years later. I was considering adding this to a python script that look for retractions and slow down the acceleration for a certain amount of distance after the extrusion, but was hoping there was some setting already implemented. Seems like there isn't I guess.