20 sided die

[Z2V]

I was in my local metal supplier today and the young lady taking my money asked me if I would consider making her a 20 sided die. I told her I had no idea what she was talking about, a 20 sided die? Some kind of table game?
Anyway, is there anybody here familiar with a 20 sided die?

 

[Aaron_W]

Bottom right

http://www.chessex.com/Dice/Opaque Dice/25404.htm


and thanks to Youtube how to make one from plywood. Digging the sound track to this one... now I want to go watch an Episode of Streets of San Francisco.

 

[Latinrascalrg1]

Here you go

 

[Z2V]

What I should have asked is has anybody made one from a solid piece of metal? Looks to be quite a challenge

 

[ericc]

Hi. It is not that difficult if you know the trick. There is a fellow on Youtube who makes these dice. The trick is to mark each face that you are making with a punch. Then, heat the ball bearing and hit it on the punch mark. Do not continue hitting! Keep moving and checking the flat spots. Eventually, they will magically grow into the appropriate polygonal faces. You have to watch the video. It is spellbinding. You will need hammer, anvil and forge. Do not get it too hot.

 

[DHarris]

I would think you could do it fairly easily if you had a rotary table & the ability to angle the cutter. They are all "flat cuts". Cut all of the top and then bottom triangles and then just match "long sides" to "long sides" of the top cuts and bottom cuts. Clear?? - - - Or, being a nube, am I missing something?

 

[Aaron_W]

The video I posted had the specs in the beginning, 30 degree equilateral triangles set at 21 degrees to each other.

How you actually do that is way beyond my meager abilities.

 

[Z2V]

Hmmm, interesting, thanks guys

 

[whitmore]

What I should have asked is has anybody made one from a solid piece of metal? Looks to be quite a challenge

I haven't done it (machined an icosahedron), but the old techniques for gem faceting ought to
handle the task. First, tack-weld a stick to the raw material block, and put that stick in a suitable (ten positions) indexing
fixture; tilt the fixture and mill the top five facets, then tilt the fixture and do five more, tilt it farther and do five more...
Then saw off the stick.
Finally, clamp the item down onto its former apex point (into a prepared seat with five
wedges) which is tilted appropriately, and mill/rotate/mill/rotate... the last five facets.

It takes four different accurate mill height settings, which can be computed with some minor difficulty.
Wedging the seat, tilting it correctly will need... geometry work.

For extra credit, substitute grinder for mill.

 

[RJSakowski]

I modeled one up in SolidWorks if anyone wants to give it a try.