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Comment by the_af | Hacker News Reader

I found this fascinating, if true:

> The reason casino dice have such sharp edges is to get the to stop rolling faster with fewer tumbling. The more a die tumbles the more likely it will present any issues with it.

If I understand it correctly, the justification is this: if a die is biased (usually a heavier face), this bias will manifest with a higher chance the longer the die rolls. But if it stops abruptly, for whatever reason (bumping against the edge of the table, other dice, or having a shape that prevents longer roll time, like the casino dice) this bias will be less likely to manifest. Did I get this explanation right?

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> The reason casino dice have such sharp edges is to get the to stop rolling faster with fewer tumbling. The more a die tumbles the more likely it will present any issues with it.

No, casino dice are flat-sided cubes because corner curvature could bias the result. Corner curvature is hard to measure. Cubical dice are easy to check for flatness and dimensions. Gambling regulators have specs for dice: 19mm, flat sides, translucent, balanced, with appropriate tolerances. Casinos usually use dice with serial numbers and logos. Casino dice come in a pack of 5 with all dice in the pack bearing the same serial, to detect substitutions.

Here's a manufacturer of casino dice, with their specs.[1]

[1] https://tcsjohnhuxley.com/product/certified-perfects-dice/

I have quite a few sets of dice for D&D, nearly all of which favour aesthetics over balance. But saying that I prefer to use simpler plastic with rounded edges at a table. Sharp edge dice stop very abruptly and tend to show bias based on how they were held. The same is true of metal dice which are heavier, and tend to land instead of roll. This isn’t really the outcome you want.

Your explanation also makes sense. Why then do casinos prefer sharp edges? Casinos strive to remove skill as much as possible.

Casinos account for this. In craps, you are expected to throw the dice such that they hit and bounce off of the farthest wall at the opposite end of the table. They may allow a roll that made it past the mid point if you just flubbed it. A short roll will not count. Dice must also be thrown and must tumble, they can't slide.

They stop sooner so more rolls per hour. House edge locks in as rolls count increases.

At least in some games, such as craps, IIRC casinos require the dice to bounce off the back wall of the rolling area.

That's how I understand it as well :)

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