What am I doing wrong with this assembly problem?

[DaveGadgeteer]

I've designed a precisely beveled pentagon and hexagon to assemble into a truncated icosahedron (soccer ball).

I can't get the assembly to work, to make the faces go together in the right places.

In this attempt, I broke the links to the original files after importing them as components, and each has a plane through each mating face as well as a perpendicular plane bisecting the face.

I copied the hexagon component and pasted it 5 times, and also made a working copy of the pentagon, which I then grounded.

I don't understand why all the hexagons have their working panes tied together--if I turn of the visibility of one plane for one instance of the hexagon, it turns off for all of them. That's not fatal, but it's probably a clue.

These hexagons can be moved independently, but they are not really independent.

I know there's no way to do this easily in Fusion, because there's no 3D snap or constraint functionality, so I have to fake it with joints and align.

Align isn't enough, because I can't align two ways at once--I can align the face planes, but if I try to align the perpendicular planes I lose the face plane alignment.

So I need a joint. I've tried putting a cylindrical joint along matching face edges, and that works until I hit OK, whereupon there's an error about removing Body1, which makes no sense to me and anyway each component has a Body1 so who knows which one the error is about.

I've tried several strategies and spent a lot of time on this, searched for methods, but no joy.

Can anyone point me in a right direction?

One puzzle is that the hexagons are not really independent. I've tried isolating them, and did break the links to the original file. How do I get several instances of a component into one assembly so that they behave sensibly?

I added the hexagon and pentagon original design files, even though I unlinked from them in the assembly, in case the problem starts inside them.

Note that the hexagon's faces are not beveled at the same angle: alternate faces bond to other hexagons, and the rest bond to pentagons. The pentagon bonds only to hexagons, so all its faces are at the same angle.

[TrippyLighting · Accepted solution]

I've looked at your files and before continuing you should familiarize yourself more with how to propery use Fusion 366's modeling tools.

That assembly would be dead easy to do using rigid joints if the bevels had the correct angles, which they don't.

However, you can still join these nicely on the beveled edges using a revolute joint.

Adding an instance (copy) of a component is done with highlighting the part in the browser and then copy and paste it. When you then edit the orignal, all the copied are changed as well.

Here is a screencast showing this.

[DaveGadgeteer]

Ouch.

Thank you!

I started over with a fresh assembly, first removing the clutter of aligning planes from the Hexagons and Pentagon and turning off the visibility of the construction features.

I wish it were possible to control those visibilities in the inserted copies, but by using Inspect to find the edges with the correct bevels I was able to do without them.

Thanks for showing me that the revolute joint would work for this. I had tried to use it and several others earlier, and was getting overconstraints and other problems. I suspect I wasn't zooming in far enough to be able to see when the joint symbol was snapping to the midpoint of the correct line.

The other thing I learned from you is that it works better to deal with joining each instance of the hex component before inserting another. I had pasted all 5 instances at once, and perhaps that muddled things. Anyway, doing it one at a time did work perfectly, and it was dead simple, as you said. 

I wasn't able to find the error you saw in my bevel angles. It is important to match the 18.68868407 degree bevels (pentagon to hexagon) with each other, and the 20.905157448 degree bevels (hexagon to hexagon) with each other. Perhaps you tried the wrong side of the hexagon? If you still think there's an error, I'd appreciate knowing what you think is incorrect.

But now that I finally have a good cluster of pentagon with its surrounding hexagons, I can start designing my gluing jigs.

Progress! I've machined all the 32 faces out of acrylic already, so I know they fit together pretty well by hand, but I have to take care that errors don't accumulate so much that they prevent the last piece from fitting perfectly. Then come the programmable LEDs. Looks like it will be ready in time for next year's holidays instead of this one, but I'll just have to gift wrap a coupon with a drawing on it!

Dave

[TrippyLighting]

You are correct. The bevels on the hexagon that looked inorrect to me at first sight are actually correct!

That only occurrect to me late when I was thinking about how to solve this differently.

Good luck with the build. It would be great to see how this progresses.

I like LEDs myself 😉