All right, I’m tired with people claiming that their dice did not produce a good number because it did not roll well. These people either do not know dice physics or are blatantly admitting that they failed to cheat.
Louis Zocci is the man who started to manufacture dice in the US. He has been innovating and retaining high quality in his products. In these two videos he explains how dice are made and gives an intro in dice physics.
In short, most common dice are wider on some of their axis. Consider a clay brick and its shape. It is a three-dimensional rectangle. Take the imaginary brick into your hand and roll it like a die. It lands on the flat side in your mind, correct? Same with dice. If one of the sides, say, 20/1 in a d20 is shorter, the dice will stop more often in those two numbers. Another thing that affects the random distribution of die faces are the edges. If the edges surrounding a die face are rounder than the others, the die will roll over that number more often, since it requires less energy to overcome gravity pulling the centre of the mass down.
Let’s observe a die. As I take one into my hand and shake it, the die should already be randomised. After all, no-one knows at this point what the number will be. After I release the die from my hand, it flies through the air, glistening in the sun or the bask of a computer monitor, and lands on a table. At this point when the die impacts the table, it is as random as possible, since no force has yet affected it apart from air currents, which are neglible. But now the die starts to travel, since it has kinetic energy left. From this point on it will try to find the lowest center of gravity. Should the die be shaped like a brick, it will be the two flat sides. And if the center of gravity is at the absolute center of the die, it will keep rolling, losing the energy in the process. And in this scenario, if the edges are equally sharp, they will all soak up equal amount of energy, and the die will land on a random side. If some side has round edges, the die will skip over that side more often. Therefore a die that rolls longer will bring biased results.
So here. The physics of a die roll. Of course, I’m not an actual physicist, so I might be completely wrong, and have just been fooled by an old guy rambling for twenty minutes. But everything stated here should be correct, so for the love of small, fluffy animals, stop saying that ‘the die did not roll well’. I hate it when people have wrong ideas.