Adding extra perimeters on overhangs
I am trying to print a model which includes an area with a steep, concave overhang. Using a small test print of only the critical section, I have tweaked the support settings to get a reasonable balance between supporting the surface and being able to remove the supports -- so far, so good.
But to ensure that I only see the contour lines (perimeters) when looking at the overhang from below, and not the hatched solid infill, I need to increase the number of perimeters in that area. Unfortunately, neither "Extra perimeters if needed", nor "Extra perimeters on overhangs", nor "Ensure vertical shell thickness" will do that automatically; none of them has any effect in this situation.
I have tried to add a box-shaped Modifier in the overhang region which sets the number of perimeters to 6 in that area. But the result is that Prusaslicer also generates internal "perimeters", which breaks the continuous actual perimeters and totally messes up the print. See the screenshot below.
Is there a way to increase only the number of "real" perimeters locally, either via some clever Modifier design or automatically on overhangs?
RE: Adding extra perimeters on overhangs
Maybe a height range modifier could help.
Is it a big part?...If not I'd just take the filament/time hit and print the entire part with 6 perimeters.
RE: Adding extra perimeters on overhangs
Thanks, @gb160!
Yes, it's a sizable model. Going from 3 to 6 perimeters globally would increase the print time from 16 to 18.5 hours, and the filament use from 400 to 560 g. And I expect to print this more than once, so spending some time on trying to optimize it makes sense.
Switching to 6 perimeters in the affected height range is probably the best compromise. That's only 5% of the model's height. I am a bit concerned about this being visible from the outside though -- I want to print with sparkly filament, which is a bit translucent. Depending on the light incidence, the internal support structure is still slightly visible through 3 perimeters.
I am a bit disappointed that the slicer cannot add perimeters automatically on overhangs. Isn't that what the "Extra perimeters on overhangs" option is meant to do? Obviously we don't want to see the infill structure from below, as shown in the "2 perimeters" screenshot here -- so more perimeters are needed to cover it?
