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gothampixel

Sweeping Vs. Jagged curve

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Posted · Sweeping Vs. Jagged curve

Can anyone explain what is going on here. Why are some curves a nice sweeping line and then jagged? It really shows up in the print. The jagged path happens in between the X and Y.

Hard to explain, see photos.

curve in Cura

result of curve in cura

thanks for your help

 

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Posted · Sweeping Vs. Jagged curve

They aren't really. The yellow line is infill, and where there is room, Cura is trying to print with it's normal 45º linear pattern, which results in those jagged sections.

Any effect you are seeing as a result is probably the infill showing through the outer wall of the print. It looks like you only have a single thickness wall, and then very high infill amount? Depending on the angle at which the infill meets the outer wall, you can get infill lines showing through the outer wall a bit. At the very least you might try reducing the infill overlap percentage. Better yet, print the part with thicker skin (i.e., more concentric passes around the perimeter) and little or no infill. Then you'll just get perimeter lines.

 

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Posted · Sweeping Vs. Jagged curve

OK - so what is a good value for infill overlap? The Help text in Cura is uninformative on the topic. And what is the value a percentage of?

 

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Posted · Sweeping Vs. Jagged curve

Generally 15% isn't too bad - but I usually use 10% now.

The value is the amount by which the center of the nozzle opening at the end of each line of infill intrudes into the width of the perimeter line adjacent to it (measured at right angles). This picture might help explain it... this shows 100% overlap - in this case, when the infill and wall are at 45º to each other. Basically the infill percentage is the amount by which the yellow dot crosses across the perimeter path (red line) that it is adjacent to - in this case, all the way.

100% overlap, off-angle

 

In this case, the line extends through the wall slightly - and in fact it is worse because the infill line does not end with a neat flat end as shown in the image, but in reality has another semicircle of plastic stuck on the outside of it (remember the yellow dot is the position of the center of the nozzle).

 

As the walls and infill become more nearly parallel at the point where they intersect, the more actual overlap there is for any given overlap percentage. At the very least, reheating the wall under pressure can start to blemish the outer wall surface... in some geometries and settings, the infill can completely protrude through the wall.

 

Playing with the overlap percentage can help, but a better solution is usually just to use thicker walls - at least two passes - so that the outer surface is further away from the infill lines.

 

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Posted · Sweeping Vs. Jagged curve

It is totally appropriate to mess with the infill overlap for this print - I would set it to 0% or even negative (if it allows negative values - it might). But make sure you put it back at 10 or 15% as if you don't, other parts will have an infill that doesn't quite touch the shell.

And again, the solution might be to set infill to 0% for this particular part and set shell thickness to say 100mm (All shell, no diagonal infill).

 

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