are dice standardized? are they warpable?

[Cthulhu's Librarian]

I've noticed this before, and after looking at a bunch of d20s, I figured that it was pretty much up to the manufacturer as to where the #s were on the dice, aside from 1 being opposite 20. I think I've go 5 or 6 different numbering patterns. Most of my dice are Chessex and they have a consistant pattern, then there are the WoTC dice, old TSR dice, and a few other companies as well. I wasn't going to include diaglos favorite, but I've got a few of those as well.

 

[Christian]

I know that a standard for d6's is that the opposing numbers add up to 7

ie - opposite the 6 is the one. Opposite the 4 is the 3.

Just FTR, there are two different configurations that follow this standard, and I've seen them both. (Have them both in my current collection, actually.) They're mirror reflections of each other, of course. I don't know which is the 'official' standard, but in this case, I'm sure there is one, at least as far as the Vegas casinos are concerned.

[edit]Just wanted to add that, while there are other possible numberings of the d6 that violate this convention, there are only two total possible numberings on a d4. Anyone want to try their hand at a formula for the possible numberings for the various polyhedrals?[/edit]

 

[DaveStebbins]

also, someone mentioned dice left in storage getting a bias, is that bogus or good science?

To add to my previous reply, bias is much more likely to come in as the die cools just before or just after coming out of the mold.

A d20, being solid, actually has a pretty thick cross-section for thermoplastics. As plastic parts cool, they shrink. The outer skin cools and solidifies first, before the part is taken out of the mold, but the inner core cools more slowly. As the innermost areas cool, they try to shrink too and this can cause some warpage or sink in some of the outer faces. For a regular polyhedron like a d20, this is probably very minor and evenly distributed, but it does happen. That's why plastic parts are usually of uniform wall thickness all around - it minimizes shrinkage distortion as the part cools.

-Dave

 

[Ferret]

So, what dice are loaded from the mold? Just hypotheticaly.

 

[DaveStebbins]

So, what dice are loaded from the mold? Just hypotheticaly.

Well that's another point, the mold itself could induce some bias into the die. If the mold was not cut correctly or, more likely, if it wears unevenly over the course of many many heats, the actual shape of the die produced could vary, introducing some bias.

In the end, given the regular shape of dice (all cross-sections through the center of a face are the same), it is unlikely that any measurable bias is introduced during cooling/shrinkage. I would expect more bias from mold wear.

Given how much plastics compounds have advanced in the last two decades, I would expect them to be fairly hardy in most environments (even storage). Due to the regular shapes, I would not expect to see bias regularly introduced by cool-down shrinkage. Even mold wear should be caught by a regular preventive maintenance schedule.

Outliers however, the occasional die which is not normal, can never be prevented. Also, given how often PM programs are more lip service than reality, I wouldn't be surprised to see biased dice made by worn molds. The only way to tell for sure is to run a test on your die and check whether your results fall within acceptable limits of "random."

-Dave
I remember altering a d20 to bias it on purpose once a long time ago, for giggles. I used it for one game session and was horrified at how amazingly well it rolled. Immediately after the game I destroyed it so I wouldn't be tempted to use it again.

 

[buzzard]

They do but the process is probably longer than the lifetime of the universe. Still, just to be safe I store all my dice with the max number facing upward.

It would not take nearly that long.

If you go to very old building(hundreds of years) with glass windows, it is visible how the bottom of panes are thicker than the tops. This is due to glass being an amorphous solid, and slowly flowing under the force of gravity. Plastics also tend to be amorphous solids. Now as to whether they would flow faster or more slowly than glass I don't know. The larger molecules of the polymers would probably slow things, but glass has much stronger bonds, so it may even out. However since nobody has multi-century old dice, I doubt it's much of a concern.

buzzard

 

[buzzard]

I know that a standard for d6's is that the opposing numbers add up to 7

ie - opposite the 6 is the one. Opposite the 4 is the 3.

I've also seen a large number of other dice, including all the standard polyhedrals, conform to this rule (ie - opposing numbers add up to one more than the maximum of the die). Most of my d20's follow this.

Interestingly enough, I think the ones which don't are the official TSR polyhedrals...

We went over our 20-siders the other night during the game session. While the majority did follow the opposites sum to 21 rule, not all of them did this.

buzzard

 

[Umbran]

If you go to very old building(hundreds of years) with glass windows, it is visible how the bottom of panes are thicker than the tops. This is due to glass being an amorphous solid, and slowly flowing under the force of gravity.

Myth. If the glass from a couple hundred years ago had flowed that much, glass from ancient Egypt or Hellenic Greece would all be puddles. And it isn't. Modern telescopy has very, very small error tolerances, and the flow of glass in mirrors and lenses would be noticed. It doesn't happen.

The old glass windowpanes is wider at the bottom becuase they were made that way. In early times, it was rather difficult to make a sheet of glass of even thickness, and some methods made a sheet that was wider on one side than the other. The folks who installed them in windows found it better to put them in wide-side down.

 

[Majere]

Myth. If the glass from a couple hundred years ago had flowed that much, glass from ancient Egypt or Hellenic Greece would all be puddles. And it isn't. Modern telescopy has very, very small error tolerances, and the flow of glass in mirrors and lenses would be noticed. It doesn't happen.

The old glass windowpanes is wider at the bottom becuase they were made that way. In early times, it was rather difficult to make a sheet of glass of even thickness, and some methods made a sheet that was wider on one side than the other. The folks who installed them in windows found it better to put them in wide-side down.

NOT a myth
Glass as a noun means a nonregular crystaline structure. That is that glass has a macro molecular structure but no repeating unit cell. This can be modeled almost exactly like marcro mollecular polymers with "croos linkages".
Glas IS a fluid and it DOES flow. It just flows extremely slowly. If you dont believe me check your double glazing in 400 years

 

[Mercule]

NOT a myth
Glass as a noun means a nonregular crystaline structure. That is that glass has a macro molecular structure but no repeating unit cell. This can be modeled almost exactly like marcro mollecular polymers with "croos linkages".
Glas IS a fluid and it DOES flow. It just flows extremely slowly. If you dont believe me check your double glazing in 400 years

Myth.

You are correct about the non-regular crystaline structure, etc. The correct term for this is "amorphous solid". It has been argued that amorphous solids should be classified as a separate state, but hasn't really been taken up by the scientific community.

If glass is a liquid please provide something along the lines of the surface tension, viscosity, or rate of flow. How long would it take for a gallon of glass to pour out of a 1" diameter hole at room temperature?

Here's one article that grants that the classification of glass as liquid or solid is hazy, but still refutes the myth that it flows.

http://math.ucr.edu/home/baez/physics/General/Glass/glass.html