Selecting the bottom edge of every half sphere

I want to fillet the bottom edge of every half sphere. But I am struggling to only select the correspondng curves. I tried using nodes to check if something was curved or not, but since the spheres intersect with a cylinder, every edge is curved. Is there a good way to get the curves I want?

Thanks!


bottom_curves.gh (138.3 KB)

I’m not sure if I understand correctly. Is it like this?

Could you attach that workflow? Or a screenshot of the result? Thanks!

bottom_curves.gh (145.1 KB)

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that is exactly what i was looking for! Thank you!

In the blue group there is an example of how the edges are selected for the fillet.
In the yellow group the criterion for selecting all the edges involved.
Here only the top and bottom circles are deleted from the selection.
There is also the coincidence of the lower edge with edges 905, 906… which gives an error.
A more accurate realization of the initial geometry would solve many problems.
Fillet_question a.gh (873.8 KB)


But the edges that cannot be smoothed must also be eliminated.

Could you describe more about what you mean of “more accurate realization of the initial geometry”? I am new to grasshopper so any suggestions are welcome.

Thanks!

In this case there are only two small improvements to make.
Leave enough space to allow the fillet.
For example between the base and the hemispheres.
The presence of the seam can cause problems with the fillet.

Make sure that the seam remains in the cut part as it already does in part of the design.
The selection of curves for the fillet will also be easier.

Got it thanks. As to the distance between spheres that was the next problem to tackle after selecting the edges.

How would you suggest moving the seams of the spheres to the optimal location?

The best thing is to redo the brep.
I don’t know the criterion you used to position the hemispheres.
In any case, cut the part of the base sphere that contains the seam, so there shouldn’t be any problems.

After I saw the first image I just couldn’t get that idea out of my head. I gave up trying to figure out how to do the fillets, but then I realized that for my purpose fillets were not needed. So I made this:


The hemispheres make a particularly nice decoration for 3D printing because insetting them just a small distance eliminates the need to print overhanging (or nearly so ) loops on the outside.

My thanks to Drew for showing this concept - I’m going to try using it on more complex base shapes.

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I too am 3d printing them, and the whole point is to be able to have the tops of the spheres open while still allowing for a vase mode print. You are correct that the fillet isn’t needed, but I am just trying to learn new grasshopper skills and selecting these edges has posed a significant challenge for me. So that’s why I keep trying :slight_smile:

If you have more cool shapes you come up with, I would love to see :slight_smile:

Well that’s an interesting idea for sure. It seems to me you’d have to have fairly large spheres to make that work. And that would require a base shape that would be too large for my printer.

This is the next level of shape I’m working on (constant convex curvature) before I try one that has both convex and concave curvature.


Placing the spheres on points on horizontal planar curves doesn’t work, so I’m thinking I’ll switch to one of the Morph components so I can use the surface’s normal vector at each location to properly orient the hemispheres.

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It actually doesn’t have to be a big sphere for it to be open. ~10mm was about the minimum for a 1mm nozzle vase mode.

That shape looks awesome. Id love if you were willing to share your workflow after you figure stuff out. I have no idea how I would do that shape :laughing:

Well I just don’t have the patience for a 0.1 mm nozzle - so I use the standard 0.4 mm ones. Even with that diameter I found vase mode to be pretty fragile, so I use a standard wall thickness of 3 loops, which typically ends up being at least 6 because I almost always have an inside and outside surface.

Making the base shape is actually quite simple: it is a Loft surface formed from 3 circles at heights of 0, 50, and 100. The top and bottom circles are 50 mm radius, and the middle one is 65mm. Right now I’ve got an unnecessarily complicated method for making the circles, but I’ll be happy to share my GH file after I fix it up a bit more.

I opted to use the Orient component instead of one of the Morph ones because I think Orient processes faster. So with that my result looks like this:


I think that is a bit better than before, but still probably not as good as a Morph would do. However, it’s not clear to me that normal people would notice the difference (whatever it might be), so I’m likely to leave it like this.

Definitely not using a 0.1mm nozzle, instead I’m using a 1.0mm nozzle. I often do 2mm wide extrusions with the 1mm nozzle too.

Looks great! Would you mind sharing the workflow? I’m interested in how you used the orient command.

Thanks!

Be careful for what you wish for!

Sure - I have no problem sharing my GH file. I post all my STL files online for free anyway - so why not? But I reckon you’ll have quite a few questions about why my GH is what it is. So feel free to ask any question.

Right now the GH is in 2 parts because I added components to make shapes like this:


But the old components are still there - just disconnected.
hemispheres.gh (24.0 KB)

Thank you!

This just finished printing:


To avoid overhangs at the bottom I had to tweak a few numbers in the Gene Pool to increase the bottom radius a small amount, and also slightly reduce the XY value for the ScaleNU component. Overall I’m quite happy with the results.

this video also explains how to improve printing