How does a d5 work?

[Gez]

I bought dice shaped like those once:

They have no chance of falling on one of the little side, so while a barrel d20 has 40 sides, it's still a d20.

 

[diaglo]

How does a d5 work?

think Dradel.

 

[Greatwyrm]

Seriously though - how else would you test them?

Dice calipers, like they use in casinos maybe?

 

[MerakSpielman]

Dice calipers, like they use in casinos maybe?

Those measure the edges, right? But when your sides aren't all the same shape or size, that can get tricky. Plus, they won't account for variations in density within the plastic, or the element of uncertainty introduced by the different numbers of edges on each side (the number of edges influences how likely it is the die will stop or find a way to keep rolling).

 

[Zander]

I talked to the guy who designed them at Gen Con. They did have someone roll the die thousands of times recording the results.

Not exactly right, but close. The person who conceived the idea is a friend of mine in Colorado. He discussed the idea with Lou Zocchi who made and markets them (probably the person you spoke to). The way they got the proportions right was to test using a machine that rolls and reads dice. The machine was invented by a Canadian physics professor. I believe that the machine can be left to run on its own. So the d5 may well have been tested thousands or even tens of thousands of times.

Here's a thread with my pic of the d5 and a few other dice from my collection.

 

[MerakSpielman]

I love those pics!

edit: Deleted a paragraph that I phrased better below when I reposted because I didn't think this post had posted when it really did so I can shut up now.

 

[MerakSpielman]

For some reason my last post didn't show up, even though the main page says I'm the last poster... I'll post it again just to be sure.

How does the numbering on the d5 work? The triangular sides are easy, just a single numeral and they can be read easily. If it lands on a rectangular side, though, an edge will be pointing up instead of a side. Do they use a variation of the way they numerate d4s, so that each rectangular side has 2 numerals and you read the right-side-up one? Or do they just have one numeral on each side, requiring you to lift up the die and look at the bottom to see what you rolled?

 

[Brown Jenkin]

Not exactly right, but close. The person who conceived the idea is a friend of mine in Colorado. He discussed the idea with Lou Zocchi who made and markets them (probably the person you spoke to). The way they got the proportions right was to test using a machine that rolls and reads dice. The machine was invented by a Canadian physics professor. I believe that the machine can be left to run on its own. So the d5 may well have been tested thousands or even tens of thousands of times.

Here's a thread with my pic of the d5 and a few other dice from my collection.

My apollogies to your friend. The guy I talked to sells lots of unusual dice. While talking he talked about working on some other new things. I may not have been paying as much attention as I should but the impression I walked away with was that he designed them. I guess I was talking with Lou Zocchi instead.

Even if the rolling was done by a machine the point was still that someone went to the effort to have the die rolled thousands of times to verify its randomness.

 

[Zander]

Or do they just have one numeral on each side, requiring you to lift up the die and look at the bottom to see what you rolled?

Yes.

 

[Zander]

Even if the rolling was done by a machine the point was still that someone went to the effort to have the die rolled thousands of times to verify its randomness.

True. It is a "fair" die. I'm not sure what standard of fairness they used: Chi-square test? Some difference of randomness test between the d5 and a conventional d6? Or some difference of randomness test between the d5 and a casino d6? My guess is Chi-square but I don't know that for a fact.