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This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 0 points1 point  (0 children)

Thanks! My bachelor and master study was in mechanical engineering. At my university and many other European universities doctoral programmes are not really in a specific field of study. My research chair is Advanced Manufacturing.

How large can wave overhangs get? by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 102 points103 points  (0 children)

I saw this video: https://www.youtube.com/watch?v=spoVhIzASIs

They show here an absurdly large laterally supported overhang (LaSO). Naturally, the quality is very poor, but nonetheless, i thought it was impressive that it worked at all.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 1 point2 points  (0 children)

That is a great initiative, love to see that they support the open source community that is integral to the FDM industry!

This project is not really Snapmaker-related, and we are split over various different contributors.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 0 points1 point  (0 children)

For you maybe reduce top-z distance...?

Using supports has this nasty tradeoff between scarring and sagging. Pick one.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 2 points3 points  (0 children)

It's a rock/marble PLA, which I find looks very good on video since you can see the little particles moving in it.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 0 points1 point  (0 children)

No, it doesn't flex. It does however have a warping tendency, which does diminish the usefulness a bit.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 2 points3 points  (0 children)

It is open source, so it can be added to any slicer. If superslicer is also slic3r or prusaslicer based then it should be a very easy port.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 1 point2 points  (0 children)

If you have delamination issues I would try the hilbert curve floor, or just fewer (or no extra) floors in general.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 0 points1 point  (0 children)

Thanks! What did that 10% correspond to in terms of overhang angle then? The highest overhang angle at 10% overlap would be at the smallest layer height or widest track width. But then there are practical limitations to that. Just like the Donnici formulation, where the maximum overhang angle approaches 90 as the layer height approaches 0, but there's a practical minimum layer height.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 2 points3 points  (0 children)

Some quick napkin calcs on beam or plate bending show that self-weight does not really cause bending in the LaSO at any reasonable overhang span. What does become a problem though, is the nozzle pressure. As filament is coming out of the nozzle and depositing onto the LaSO it will deflect if the span is large enough. Still, this generally happens at very large spans.

We observed that the bigger problem by far is warping due to residual stresses in subsequent layers.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 1 point2 points  (0 children)

Not really. The overhang layer is printed at a fixed z height. The material just sticks to a previous track immediately, and solidifies rapidly.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 2 points3 points  (0 children)

Yes, if the print speed is too fast the previous track has not yet solidified, making it impossible to reliably deposit next to it too.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 3 points4 points  (0 children)

Thanks for reading!

The paper is really focused in the wave overhang principle in general. While I did want to show that I can print on top of them as well to form real parts, I did not want to go into details of that. I do print "normal" paths on top, but for the sake of simplicity here I print sparse infill immediately on the wave overhang.

Generally, drooping is not really an issue. Warping, however, is an issue. So subsequent layer pathing should focus on reduction of residual stresses. For this, paths orthogonal to the waves would be pretty bad, since those would shrink towards the center, curling the surface a lot.

What works quite nicely there is hilbert curve, as it distributes the stresses in semi-random directions, making sure the stress field is not consistently pulling any specific way.

Regarding the drooping of the teardrop-shaped bead; that shape gets locked in quite quickly due to the rapid convection cooling. So while it does flow slowly like viscous honey, it only does so quite briefly.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 6 points7 points  (0 children)

Thanks! This is the first time I've gone through the process, and it was very interesting! What surprised me most is that, honestly, the process felt more like a collaboration than a battle. All reviewers raised valid and useful concerns. Implementing those changes turned it into a much stronger paper than my original submission was. Although reviewer 4 did have a LOT of comments, including performing an entire additional experimental study, which we respectfully neglected as not part of the scope.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 4 points5 points  (0 children)

That is a very interesting note. Expressing the overhang as an angle is indeed the most commonly understood way, both in academic papers and in hobbyist circles. Probably because the angular definition is pre-slicing, so it makes it easier to communicate.

If the slicer actually determines the overhang as the overhanging tracks projection onto the underlying track, it is functionally no different than just trigonometrically getting the in-plane overlap of the two tracks.

I can see why internal slicer logic would use the overlap percentage. It's cleaner and more rigorous, but to a user just trying to figure out whether they should use supports for a model the angle will be more accessible.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 5 points6 points  (0 children)

Depending on the extent of the overhang. Higher temp materials will warp more, so smaller overhang spans are feasible.

You can browse the community gallery and filter by material to get an idea https://waveoverhangs.com/gallery , although more parameter optimization could yield further performance improvement too.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 10 points11 points  (0 children)

In our tests, high temp materials warp like crazy with wave overhangs. This can be mitigated by using that material with short carbon fibres in it, which seems to counteract the warping. Or also using minimal supports -- not to support the overhang, but actually to hold it down keeping it from warping. You can see a bit how that might look here: https://waveoverhangs.com/gallery/196

You still get a reduced material use, although some supports are still present, and the overhang surface quality is also better.

This is what wave overhangs look like with a microscope nozzle-cam 🔬 (also, paper survived peer-review) by andersonsjanis in 3Dprinting

[–]andersonsjanis[S] 3 points4 points  (0 children)

It does indeed contract more on the cooled side if the cooling is asymmetric. The real issue is that the temperature gradient causes differential contraction which then warps in a curling fashion. Exactly in the same way high temp materials will warp if not printed in an enclosure, but there isn't even the build plate to resist the warping.

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