From cube-lovers-errors@mc.lcs.mit.edu Tue Jul 29 10:52:34 1997 Return-Path: Received: from sun30.aic.nrl.navy.mil by mc.lcs.mit.edu (8.8.1/mc) with SMTP id KAA09946; Tue, 29 Jul 1997 10:52:33 -0400 (EDT) Precedence: bulk Errors-To: cube-lovers-errors@mc.lcs.mit.edu Mail-from: From nbodley@tiac.net Tue Jul 29 03:22:14 1997 Date: Tue, 29 Jul 1997 03:10:32 -0400 (EDT) From: Nicholas Bodley To: Corey Folkerts Cc: Cube-Lovers@ai.mit.edu Subject: Re: 2^3 Reassembly In-Reply-To: <199707280518_MC2-1BB6-48C8@compuserve.com> Message-Id: My, it's been a while since I opened up mine. I hope I remember. What perplexes me (I was about to say, "puzzles me") is that I don't recall how it could be assembled wrong; surely there aren't two internal mechanisms that differ in some details? Perhaps it would help if I describe the internal structure (from memory). The basic structure that I remember is built on a "jack"; it's basically mutually-orthogonal extensions from a center, so to speak; like a physical embodiment of the axes of 3-D Cartesian coordinates. What I recall is that three of these, all adjacent, have a square cross-section; the other three have a circular cross-section, with a diameter significantly smaller than a side of the square. Each of three round projections fits into a hole through a rotating long, thin square prism. (In the vernacular, square sticks with round holes through their centers.) In mine, I am just about certain that all of these had the same length. Each cubie (all were identical internally) is hollow, but cut away with concave arcs that allow them to turn with respect to their neighbors. The cubies are kept together by 12 "clips". These fit into the cutout arcs; when you assemble the Cube, you put two cubies next to each other (they touch) and fit this "clip" so that it keep s them together. To install it, you move the clip away from the imaginary geometrical center of the whole puzzle. As I recall them, the "clips" are essentially quadrants (1/4 circles). They consist of two parallel planes with a gap between them; the sides of the cubies fit into this gap. The parallel planes are joined at the inner edges. When the whole Cube is assembled, the square extensions of the "jack", as well as the square sticks that turn on the other ends of the jack serve to keep the clips from moving toward the center of the whole Cube. This is a structure that could not be either assembled or disassembled if it were made of rigid materials. It's only because the cubies (at least!) are made of a strong plastic that has good mechanical spring properties and can be harmlessly deformed (within limits), that it is possible to make this structure. >>> It's conceivable that the cube was misassembled so that one or more "clips" didn't actually straddle both of its cubies. When assembled, there should not be any gaps between the cubies, and all movement should be reasonably free of friction. I'd love to know how these were assembled in the first place; did the mfr. have special tools to temporarily deform the parts? Did the assemblers develop very strong hand muscles? Btw, it's a challenge to describe the innards in words. I hope this helps! |* 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 1 B.C.E. --------------------------------------------------------------------------