How can I shell objects to maintain a XY dimension thickness to optimize for thin walled 3D printing

andrew_slovak

Hi all. I'm trying to design things for 3d printing. I want to be able to shell an object so that the on the plane of each layer, the thickness is equal to a multiple of the nozzle width, so that it can perfectly lay down a single or multiple perimeters perfectly. Currently, when I shell an object, it makes it so that the thickness is the value I set normal to the wall, which is obviously the intended behavior, but it means that for anything on an angle relative to the plane of the layer lines, the shell is thicker than the desired value. I could do some trigonometry to figure out the correct shell thickness to ensure a 0.4 XY thickness, but that wouldn't work for curved parts or parts with varying angles. Below is a very crude paint drawing to try to help visualize what I'm looking for.

nick_papageorge073

You're overthinking it. It won't make any difference to the printed parts. Printing is +/- a lot anyway.

_anton

+1 for Nick. If the goal is to save material or increase strength, there isn't much to be gained there. If it's to minimize small bits of infill (actually an annoying issue in my experience), you can twiddle your infill settings.

martin_kopplow

I know this is annoying when printing, but you can't create a wall thickness that creates a multiple of the nozzle diameter at all places. It could be possible for planar faces and constant angles, but at least at those places where the shape goes from one angle to another, or if it is an organic shape of any kind, there will be tiny bits of infill you'll have to deal with.

_anton

Algorithmically, it should be possible for your slicer to do a vase mode with multiple concentric walls and zero infill. AFAIK, though, at least Cura doesn't allow that.

martin_kopplow

Yes, definitely a job for the slicer, but expect to get bumps on one side of the shape: The switch from e.g. wall thickness = 3 x nozzle to 4 x nozzle diameter will certainly be noticeable, and can't probably be avoided in all shapes.

andrew_slovak

Hey guys, thanks for the responses! What's actually happening is when I add 0.8mm ribs to strengthen my thin walled objects, unless the ribs are perfectly vertical I get annoying infill. It's annoying because it results in artifacts on the print that wouldn't be there otherwise, since the print head has to do a retraction and make a travel move rather than just making all perimeters. If I simply remove the infill then I get a gap and compromise the strength of the part. All that being said, I'll take what y'all have said I to consideration and potentially try some other things.

nick_papageorge073

Feel free to link your part, maybe we can give ideas.

For what it's worth, I have an injection molding background, where wall thickness being consistent is rule #1, and when strength is needed, to add thinner ribs. When I started designing for my personal 3D printer for home hobby work, I was designing my parts about the same way.

Then I realized I wasn't really saving printing time, and I was adding design complexity.  I've done time comparisons in the slicer, and often it is almost just as fast to print a "block" with 15% infill, rather than make a shelled version of that block with a wall thickness of about 2-3mm. I was quite surprised at this, and it has helped my "design for 3D printing" mindset to keep things simple.

sebastian_glanzner

Hi @andrew_slovak I also would like to have a function to shell it with the same thickness in XY-Plane. That will speed up the print and make it cleaner, I agree.

I don't know what slicer you use, but a few of them have a function to vary the line width to reduce unecessary infill.
In the Bambu Studio it is called "Arachne" and this was adopted from other slicers: