How to print an overhanging arc

  • I am designing a part that has to clamp around a 11mm bushing, and due to other design constraints, it has to be printed with a semicircle-shaped overhang:

    enter image description here

    This is proving very challenging to print. Two copies of this part have to clamp tightly around the bushing in all directions. Support material is rather hard to remove from the very top of the arc (where the overhang angle is the highest) and I often end up removing just too little of the support material (so the part doesn't fit around the bushing) or too much (and the bushing can wobble around).

    Is there any way I can modify the design of this part (bearing in mind that it absolutely has to be printed in this orientation) to make it more tolerant of my inaccuracy when removing supports, or is there perhaps some way to manually design supports that are easier to remove (Simplify3D and Cura both don't quite cut it)?

    Is it possible to print it laying down so that your arch is not built over open air? If not, why not?

    @MattClark No, and the reason is not relevant to the question. The part shown here is oversimplified, the real part has additional geometry that makes printing in any other orientation impossible.

    could you briefly explain why it has to be printed in exactly that orientation?

    The part is under a lot of strain, if I printed it in a different orientation it would delaminate too easily. The scope of this question is *only* about possible ways to get this to print acceptably in this specific orientation, I do not care about any other solution. It might be possible to redesign the part to not require this orientation but I can just barely get a good enough print this way, so something that drastic isn't needed, but I'd still like to know if I could improve it without too much effort.

    What does this additional geometry look like?

    @thethirddimension It's irrelevant - please don't try to sidestep the question. It needs to be printed in this orientation, period. I might be suffering from the XY-problem, but I am generally just curious if there's a way to get this kind of geometry to print better than jus using supports. I am not interested in overhauling the entire part.

    I wasn't really a fan of cura and I never used simplify3d, but Slic3r may solve some of your problems. Notably, setting interface layers to 2 or 3 will make it easier to remove support material.

  • tjb1

    tjb1 Correct answer

    7 years ago

    You could modify it as shown in my picture. I added lines tangent to the 11mm circle and in this example I set them to a 40 degree overhang which should be fine, the top line is also tangent to the circle and in my experience it's easier to bridge a small section rather than do a bunch of small overhangs like an arc would do. You still end up with quite a bit of contact but also easy to print.

    I did something similar to this on my printer where the smooth rods enter horizontal holes.

    Angled Overhang

License under CC-BY-SA with attribution

Content dated before 7/24/2021 11:53 AM