Tony Fisher wrote:
Yes, there is a basic rule-
1. Where technology and costs allow it should fit into your hand perfectly for turning.
2. If no.1 means parts are too small increase overall size until parts are no longer too small.
Sorry if that's not the maths you were looking for.
I tend to agree... but it appears most manufactures don't follow something quite so simple. If the ideal cubic puzzle is (57mm)^3 then why isn't the 2x2x2 also (57mm)^3?
Anyways... googling I've found all of these reported at the edge length of the "classic" Rubik's cube (55mm, 56mm, 57mm, 59mm, and 2.2 inches). Not sure if there was that much variability in the manufacturing process or what but I did find that odd.
There is also the question of when is a part "too small". Does it interfere with function/turning? Is its surface area too small for a sticker to reliability stay stuck? Are they in danger of being lost should the puzzle pop? Likely some combination of all these factors.
Granted these are all very subjective questions and they will very based on the method of production too (injected molded, 3D printed, cast, etc.).
I wasn't expecting a hard fixed rule everyone was following but I was curious what if anything the general trend might tell us.