Just wondering. Has the Skewb patent expired, like the Megaminx's for example? What's the site policy on them?
The patent I believe we can attribute to the Skewb was obtained on October 25, 1994 based on this
link (patent #5358247, link courtesy of the wonderful TwistyPuzzles patent page
) to a puzzle ball patent Meffert has.
Note that although the popular name is "Puzzle Ball" and "sphere" is used throughout to describe the shape, at the end of the patent you will find:
Skewb patent wrote:
Furthermore, the use of a three dimensional representation on the surface of a spherical puzzle is not to be construed as limitative and is applicable for use with other forms of rotating puzzle, for example on puzzles of any polyhedral form.
One can assume a patent lives up to 20 years, but that is only with all the proper fees paid. In this case we can find patent 5358247 expired in 2002 based on this
Our site does not require a patent for us to consider copies KO, but if a puzzle has a patent we do respect that this is a contract the creator makes with a government (or governments) and therefore when it expires that is compelling evidence to consider the creator acknowledges they are giving up their limited monopoly. As such we don't consider 3x3x3 or Megaminx copies KO.
I think the reason a patent expires before the full limit is something we would take into consideration. If it expires for lack of payment because KOs ruin the market for the creator I think we would be pretty sympathetic and may still consider copies KO.
We have not traditionally considered Skewb based mechanism puzzles (there are so many shape mods) KO, nor even the copy of the traditional square classic. I have not spoken to Uwe about why the patent was allowed to lapse but if he were to contact me of course I would be happy to hear him out on his perspective.