From cube-lovers-errors@curry.epilogue.com Sat Oct 26 00:18:08 1996 Return-Path: cube-lovers-errors@curry.epilogue.com Received: from curry.epilogue.com (localhost [127.0.0.1]) by curry.epilogue.com (8.6.12/8.6.12) with SMTP id AAA03251; Sat, 26 Oct 1996 00:18:08 -0400 Precedence: bulk Errors-To: cube-lovers-errors@curry.epilogue.com Date: Fri, 25 Oct 1996 23:47:50 -0400 (EDT) From: Nicholas Bodley To: Wei-Hwa Huang cc: Cube-Lovers@ai.mit.edu Subject: Re: Siamese Rubik's Cubes (was Re: DEAR TANOFF <(fwd)) In-Reply-To: <54qh9o$4tu@gap.cco.caltech.edu> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII On 25 Oct 1996, Wei-Hwa Huang wrote: }Norman Diamond 25-Oct-1996 1355 writes: }>A. Southern misinterpreted M. Velucchi's picture: {Snips} }A "creative" question: } }Suppose we want to be able to rotate the 17-cubie faces 180 degrees. }Can anyone think of a mechanical structure that could achieve this? Here's hoping that this "stream of consciousness with revisions" style is acceptable!: I can conceive of such a structure, but whether it could be made to work decently is quite open to doubt. It would have a great many pieces; the whole top layer would have to consist of cubies with two physical parts, one that would travel to its new location, and the other which would remain behind. Holding the whole works together while rotating it is difficult enough, but reliably reattaching the two parts of each cubie once the rotation was complete is borderline crazy! Of course, all edge and corner cubies would need to be two-part. If someone is ambitious enough to attempt such a design, it would be very costly and out of the question for mass production. It might help if a tool (such as a Torx (TM) wrench) were provided to insert into both "face-center" cubies (or the common corner cubie) to unlock the top layer from its underlying parts and to lock the top-layer cubies together. However, just a clamping frame to hold the top layer together would make sense, IMO. A strictly-mechanical solution is at least borderline impractical, but shrewd design with rare-earth magnets might help. Dismantle a regular Cube to see what would be involved. An edge cubie has a "foot" that extends below the top layer, as does a corner cubie. These "feet" would have to be left behind once a move began. It's really nice to have all the unlocking and reattaching taken care of "automatically" by just the twisting shear force created by gripping the Siamese Cube, but for such a move as this, that's a formidable luxury. If I were an experienced mechanical engineer, I'd say it just isn't practical. However, it is great fun to think of how it could be done. (If e-mail had a universal graphics format, illustrations would be nice, but I honestly don't feel that ambitious!) I also suspect that when it came time to design in detail, new conceptual problems would arise which might be extremely difficult to overcome. Consider, for instance, that if you don't use a clamping frame, the mere act of locking the top layer together has to hold the corner cubies in place. The locking pieces need to be operated by sliding members passing through the neighboring edge cubies, and that's not all, by far. My regards to all, |* Nicholas Bodley *|* Electronic Technician {*} Autodidact & Polymath |* Waltham, Mass. *|* ----------------------------------------------- |* nbodley@tiac.net *|* When the year 2000 begins, we'll celebrate |* Amateur musician *|* the 2000th anniversary of the year 0. --------------------------------------------------------------------------