Is a dodecahedron possible?

Hi, I love the UI & UX of shapr3d. I have never enjoyed auto cad’s UIUX and it turned me off from doing cad work myself.

I’m working on a simple design right now to learn the program, or so I thought.

The goal is the Platonic solid of the dodecahedron.

I need a handful of versions

  1. Made of faces: actually 12 pentagon bodies with a depth that is proportional to the radius. Technically I only need a single body that can be mirrored around the side surface. Can this be done as simply as sketching a pentagon then a second and lofting them? I tried this and failed to get the proper angle the times I tried.

  2. Skeleton version: basically offset edge of face from first to create a center void?

  3. Solid single unit.

  4. Solid dodecahedron fitting inside the first on the list.

I want to thank the team behind shapr. Creating a beautiful Intuitive CAD program is game changing. It’s helped me more easily begin to properly learn CAD.

I’m currently renovating my home. Before attempting the dodecahedron I used shapr and magicplan to create models of the condo. With these I have modeled new custom furniture. One of the pieces, my entertainment wall, will be my first project from start to finish on shapr3d that is a real object. The design is simple, but it’s very rewarding to know how much I’ve learned about CAD so far. Shapr allowed me to model the unit while in the lumbar yard parking lot to double check everything and make my cut list (had them cut down plywood sheets to save time on my end).

In short, what am I missing with the dodecahedron? I’ve tried many ways and have yet to achieve perfection. I can believe I can upload the files if that’s of use.

Succinctly,
-Andrew

Hi Andrew,
I found this to be an interesting challenge. But I think I figured out at least the first part. A body to mirror to make the full dodecahedron.


Start with a pentagon.
Make a copy of the pentagon by rotating from an edge 116.56505*.
Add a midplane between both pentagon sketches.

Rotate and copy the new plane 72*. Repeat 3 more times.

Extrude a body from the first pentagon sketch. Use the planes and Split Body tool to make the pentagon body for mirroring.

Select the body and mirror on any face until the dodecahedron is complete.

I’m using Shapr3D to design and build our house as well. It’s an amazing tool. Being able to build anything here first helps to find issues before costly materials and time are wasted. The topography was a fun modeling challenge as well.

3 Likes

Thank you for your reply.
I have tried this method, however, I used 5 sketches mirrored on the base sketch. Planes may be better to use.

My biggest takeaway is one question, how are you able to input the angle of rotation as the full decimal? Mine always rounds it to 116.57 even when I type out the full number. I also tried converting it to fractional notation but it failed.

I believe this is the issue. Is there a setting or configuration I can change? I am on my macbook Prousing shaper.

Also, would it be possible to share the shaper file with each step so I can try and figure out what my problem is?

Your house model looks incredible. Right now I’m just doing a condo so no terrain.

Succintly,
-Andrew

I just followed your steps to the letter and it worked perfectly.

I’m not sure what my issue has been. It accepted the full dihedral angle this time, in the past, it did not.

Using planes vs sketches as split surfaces may have helped.

Prior to the split tool, I was doing some very very funky stuff and none of it worked quite right.

Thank you for taking the time to give it a go. I owe you one.

Succinctly,
-Andrew

Glad it worked!
Ive found that dimensions, angles, and such can be inputted to greater accuracy than is displayed.
The Split Body tool is a game changer.
Looking forward to all the neat toys and tools the Shapr3D team can come up with.

Thanks for the compliment on the house. It’s been an… adventure :joy:

Yeah, it has made it much easier. Your method was better than using sketches, it’s going to be how I do it from now on. I like the logic of it.

For some reason, I forgot that dodecahedrons do not tessellate! I think part of my issue when I made mine was I expected them to do so.

However, I was still getting messed up with pentagonal pyramids for some reason.

While it probably isn’t true, it seems minor things are tweaked in each minor update and the unit specificity does. That’s likely completely wrong, but it seems half the time units auto round and sometimes they don’t.

It also drives me nuts you cant paste the number in, and copy numbers.

I love the UI but the lack of many features has got me using Fusion 360 as well. I wish it weren’t so. Shapr is great as a basic starting point before going too detailed and whatnot. I like it a lot and am considering getting an iPad Pro just to use shapr on.

Obviously, I’m conflicted. Like the fact that I cant seem to figure out how to export just a single body from a document. However, I believe that’s on my end and a lack of know-how.

Succinctly,
-Andrew