# Making 20 sided Dice?



## WoodSpanker

I was building a display case for client to display his Dungeons and Dragons miniatures in. He was impressed by my work, and asked me to make him a complete set of D&D Dice for playing the game out of wood (Specifically, Ebony). For this he wants to pay me much money! But I looked at a 20 sided die, (and most of the OTHER dice, for that matter) and have no idea where to even begin. Does anyone have ANY idea how I would go about making such complex little polyhedron?


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## Loren

Perfect reason to invest in a CNC machine.


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## WoodSpanker

lol Loren, yes well, CNC's are just a bit out of my price range. o.k., more than a bit.


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## RogerM

Woodspanker - What you are considering is called an icosahedron. You can find a lot of information about these geometric figures at http://en.wikipedia.org/wiki/Icosahedron. This website portrays many of the angles that you will need in making the item that you are considering. If you are versed in geometry and a little trigonometry you should be able to determine the cutting angles. This polyhedron has 20 identical equilateral triangular faces, 30 edges and 12 vertices. I have made these as wooden plant holders but never a die. If I can be of further assistance please feel free to contact me.


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## helluvawreck

I just looked at that page and and it looks like you have a tall order on your hands. Good luck.

helluvawreck
https://woodworkingexpo.wordpress.com


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## lew

I know it is not the same thing but this might give you a starting point-
http://www.magicalwoodproducts.com/dodecahedron.html


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## Loren

I think perhaps the easiest way to make a one-off in a small
size would be to make a sphere, plot out the intersections
on the surface, and use a chisel to make a flat between each
set of 3 points.


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## Tootles

That does look tricky. What size does it need to be?

Looking at the animation that RogerM pointed to, it looks as though you could start this on a lathe (you'd probably need to have a chuck). There are ten triangles around the outside of a cylinder and then each end has five triangles meeting at a point. So if you started with a cylinder that has a cone on each end you would, as suggested above, need to mark the vertices and then either chisel or file the faces flat.


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## 280305

I will be keeping an eye on this conversation. My 9-year old is very much into D&D. When he saw this, he said, "I think that some numbers will come up more often than others". Which is a good point. Since this is not just something to look at, it is not enough that the dice look regular. They have to be regular in many subtle details such as the rounding of the edges.

I hope you are able to find a solution.


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## nick85

This may be a stupid idea, but why not cut out 20 equilateral triangles from a thin board, miter the edges, and assemble them?

Or alternatively, using the net from http://en.wikipedia.org/wiki/Icosahedron, trace the pattern on a thin piece of wood. Go over the edges with a chamfer bit just far enough to let the wood fold, but not through. Then fold the net onto itself to create the icosahedron…


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## WoodSpanker

Thank you all for the wonderful Ideas! I shall have to try them all until I find the solution. (on pine, of course). SO far, Nick85's idea sounds like the best… though glue up might be a bit of a problem. IF it works, however, then it is GOLDEN!  I will have to figure out something to fill the empty middle with, so that the dice have some heft to them.


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## SugarbeatCo

epoxy?


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## nick85

Would it be cheating if you laminated over an official D&D die? xD

I think if I were to do it, I would assemble 19 faces, and before placing the 20th, fill the cavity with epoxy or resin (although depending on the size and thickness of the wood, resin may heat up too much and warp the figure.) After placing the last face on, add the numbers, and dip the die in some high-build crystal-clear epoxy. Just keep twirling it around like you're at a rave so you don't get any runs…


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## IrreverentJack

I'd look into using a combination of Martin's EZ Mitre Technique and Nick85's triangles. Route out the numbers while the board is still flat. You'll need a few jigs and a very accurate saw. Looks like a fun project. -Jack


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## Tootles

I did some fiddling on Sketchup and came up with the interrior angle between adjacent surfaces being approximately 140°. So a standard 45° v-groove bit will take off too much wood from the edge. That may mean that you need to use an epoxy or other glue that fills gaps rather than a pva type glue.


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## WoodSpanker

epoxy and pre cut triangles it is. Thanks all, I'll let you know how it turns out.


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## derosa

Good luck with this. I would maybe try a 4 sided, 10 sided not likely, wouldn't even want to contemplate 20 sided. At least he didn't ask for the 100 sided die, a real one looks like a large marble with facets just big enough to fit a number in. Also remember that opposite sides total 21, don't want to put in that much effort and discover it is numbered wrong.


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## JGM0658

If you had one of these you could make it easily as it has the capability of cutting very small pieces. Certainly not a tool to buy for a one off project though.. 

http://www.bridgecitytools.com/default/tools/jointmaker/jointmakers.html


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## WoodSpanker

At $1400, no it's not worth buying it for this one project.


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## nick85

Any progress on the dice? The nerd in me is really interested in seeing the final result… =)


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## Mike9214

Okay… Here is the kicker and actually very easy to make the triangles with a table saw….

there are 20 different Equilateral triangles in this thing… So all sides are the same… Here is what you do:

I am making one now for my kid and this is what I have figured out…
I will use my numbers to show the example…

1.) Figure out the length of the sides… In my case I made it 9"

2.) Figure out the height of the triangle… (now here is where math comes in to play)
on your calculator, punch in 3 and then square it… times it by the length of a side (9) and then divide by two…

3.) Now you have a decimal of the height to get it in inches for the table saw go to:
http://syzygy.virtualave.net/webwork/javascript/decin2fr.html... in the first space put in your answer and leave the second number set to "16". this will give you the inches in full inches and then the remaining 1/16th of an inch(s)

4.) That number is what you want to set your rip fence at and then rip a strip of material…

5.) Now the inventive part… set your miter to 30 degrees… Set the rip fence to exactly one half of the number you have from step 3. and line up the strip of material against the miter and the corner against the rip fence.

6.) Now move the rip fence back to the original measurement from #3. Flip the material over and line up the strip of material against the miter and the corner against the rip fence.

You have a perfect equilateral triangle.

Now to join them all together? you need to put a 30 degree cut on each edge where they join together… Your choice on either sanding or set blade to rip each side…

Laying the pieces down on a flat solid surface, tape the edges together, apply glue and then just bring the taped pieces into a ball and tape closed until dry…

Sand edges just enough to take the sharpness off…

I hope it works for you…

Rule of thumb is the length of a single side will be approx. half the height of the finished product… So my 9 inch triangle will make an 18 inch high 20 sided die…


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