I asked on a facebook group what slicers do if the line width isn’t divisible by the nozzle width size. Only got one response from someone that says cura will print thinner lines. Does anyone know more about this? Seems very common.
It ignores the line and doesn’t print it. So the thinnest a 0.4 nozzle will be sliced for is a 0.4mm wall.
@Michael_Scholtz what if it’s .6 line and .4 nozzle?
+Peter van der Walt s3d doesn’t
I generally figured that trying to get too narrow of a bead width would compromise the surface finish. What does the part look like if your bead is narrower than the orifice?
Like others have stated most slicers ignore the line and don’t print it. In a slicer like Cura if you have built in thin wall supports they need to be .45 thick for a 0.4mm nozzle to pick them up and print properly. This is partly to accommodate the fact that what gets extruded out of a .4mm nozzle is larger than .4 due to pressure expansion of the molten plastic. You will typically get a .45 - .48mm diameter extruded strand if there are not other issues with your extruder. Some slicers take this into account to preserve fine details.
There is a work around to this to get thinner lines out of a .4mm nozzle. Tell the slicer you have a .3mm nozzle and then jack up the filament size from 1.75 to 1.85 or 1.88 (thinks it is over extruding and pushes out less) and you can get really fine detail. The print time goes way up and it is better to use an actual 0.3mm nozzle but in a pinch to capture detail…
If the line is wider than the nozzle, 0.6 for example, Cura will either print a single line (about .5mm) or two lines with a large overlap (.7mm). I’m not sure how it decides what to do as I have seen both results with thin wall print tests.
On layers, if a sliced model feature is not a full layer height tall it will print thicker than designed if the slice of model is more than 50% of the layer thickness. If it is less then it will get skipped. This is at least true on 0.1mm layer thickness prints.
@Jeff_Parish why would you need to under extrude? If it thinks it’s .3 than it will print less by default.
@Dovid_Teitelbaum That is what worked for me. There may be other ways or settings to get the same end effect but simply designating a smaller nozzle and not changing the apparent diameter of the filament printed messy. Under extruding solved the problem.