Extra parts for the compound of five squares

The place to talk about Stella4D, Great Stella, and Small Stella. Feel free to ask questions about them here.
Post Reply
TomF
Posts: 8
Joined: Tue Dec 28, 2021 4:34 am

Extra parts for the compound of five squares

Post by TomF » Sun Jan 15, 2023 5:44 am

I have the feeling the I'm asking a stupid question, but here goes.
I'm making a compound of five squares and am following the suggestions in the gallery. I've made the twelve components of that figure without difficulty, but am struggling to understand how to make the star-shaped extra parts that are described there. I have the feeling that it's some form of faceting, but doing that is still beyond me.

User avatar
robertw
Site Admin
Posts: 676
Joined: Thu Jan 10, 2008 6:47 am
Location: Melbourne, Australia
Contact:

Re: Extra parts for the compound of five squares

Post by robertw » Sun Jan 15, 2023 8:13 am

Squares are flat. Do you mean the compound of 5 cubes?

https://www.software3d.com/5Cube.php

I think you are asking about the extra white parts I used to add strength inside, and help to get the last part in, as seen in image below, with description "For added strength, and keeping in mind how I will get the last piece in, I printed some extra parts for added internal strength. Here is one such part, which attaches to the part above".

Image

I can't remember exactly how I made those parts, but here's 2 options for the main part.

(1) I think you can just use the nets of the Great Dodecahemidodecahedron (I think the dimensions match, and this is probably what I did).

Image


(2) Otherwise, to create them from first principles, the following could be done.

Drop to 5-fold dihedral symmetry, and display the symmetry axes. Use faceting mode, and open a faceting view. Switch the main view to a stellation view as well, or use Shift+V to display stellation vertices in the base view. This is so we can click on the points that look like vertices but aren't really, where faces intersect. The facet you want to create is like below, and make sure it's near the 5-fold axis:

Image

Accepting that facet and you should see this:

Image

The green edges are unmatched, so we need some more faces just to make this an acceptable polyhedron. You can create triangles like below. If you have "Maintain Reflexibility" enabled, then you'll only have to draw one (otherwise two).

Image

Now you can make this the new base model and create its nets. I found it didn't want to joint the red darts together at first, but drop to 5-fold pyramidal symmetry and then it works.

Image

You could go to the trouble of adding more faces to cut the tip off the darts, but you can also just cut the tips off about halfway when cutting them out. Otherwise all the dart tips will meet in the centre of the model, which should work in theory, but in practice probably better if they don't.

TomF
Posts: 8
Joined: Tue Dec 28, 2021 4:34 am

Re: Extra parts for the compound of five squares

Post by TomF » Tue Jan 17, 2023 3:16 am

Thank you, Robert.
You're absolutely right. I should have said cubes instead of squares. That will teach me to violate my rule of never posting anything after dinner.
I'll give your suggestions a try ASAP. I particularly like the first one. I would never have thought of that approach and it shows how to address similar problems with other figures in the future.

TomF
Posts: 8
Joined: Tue Dec 28, 2021 4:34 am

Re: Extra parts for the compound of five squares

Post by TomF » Tue Jan 17, 2023 11:00 pm

One more question if you don't mind. How did you produce the net in your post? When I pull up W102 in Great Stella, it produces this figure and net:
Image

Image
I can use this of course, but the one you have makes for a neater net and less gluing. I've tried using cut/uncut, but that doesn't seem to have any effect on this net.

User avatar
robertw
Site Admin
Posts: 676
Joined: Thu Jan 10, 2008 6:47 am
Location: Melbourne, Australia
Contact:

Re: Extra parts for the compound of five squares

Post by robertw » Wed Jan 18, 2023 12:12 pm

Change this setting. Because the edges coincide with another edge behind them, it is splitting the nets so that there will be tabs behind to attach internally for extra support.

Image

Post Reply