From cube-lovers-errors@mc.lcs.mit.edu Sun Jul 27 21:38:21 1997 Return-Path: Received: from sun30.aic.nrl.navy.mil by mc.lcs.mit.edu (8.8.1/mc) with SMTP id VAA29673; Sun, 27 Jul 1997 21:38:20 -0400 (EDT) Precedence: bulk Errors-To: cube-lovers-errors@mc.lcs.mit.edu Mail-from: From nbodley@tiac.net Sun Jul 27 20:25:05 1997 Date: Sun, 27 Jul 1997 20:21:46 -0400 (EDT) From: Nicholas Bodley Reply-To: Nicholas Bodley To: Cube Mailing List Cc: Javier Susaeta , Mark Glusker Subject: Making parts for puzzles (somewhat off-topic) (medium length) Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII For reasons I'm not certain of, but probably having to do with a case of brain fade caused by not eating a proper breakfast (I live alone!), I posted a short article to the wrong mailing list, no less. It was to an unmoderated list that goes to people interested in mechanical calculators, so the few replies I have had so far found it interesting. I do hope this is not too far off-topic; I have included replies that contain material that would be helpful to anyone who has any ideas for making new or replacement parts, and has access to the technologies. The length is not hopeless... Subject: Rapid Prototyping and conceivable Cube reissues (Posted 09:53 AM 27/07/97 -0700 with follow-up (by gracious permission) from a couple of people who >do< know what they're talking about.) This is close to being peripheral to the topics of the List, but it might be worth pointing out that it is now possible by several methods to "print" solid objects in 3 dimensions from digital data in the proper format. I'm fairly sure it's even possible to make molds. These processes are sometimes known as Rapid Prototyping, and (betraying linguistic ignorance or lack of concern) something like 3-D Lithography. ("Lithography" has roots meaning writing on stone.) (I suggest Solid Object Synthesis...) The field is still evolving and improving. The data files for these processes are ordinarily created by CAD (Computer-Aided Design/Drafting) programs. The programs create the data for numerous thin slices of an object. The data for a slice directs the machine to make a solid counterpart, and the object is created progressively by creating a bonded stack of the requisite number of slices. (I shouldn't go into how, but one early method uses a pool of photopolymer and a flat "stage" that progressively moves deeper into the pool. A bright UV light source positioned by the data triggers polymerization (solidifies).) My point is that it is now considerably less expensive and much quicker than it used to be, to make a prototype of a puzzle design, although the materials used for this process (afaik) don't have the requisite durability yet. With copyrights taken care of, it might be possible to make limited numbers of given designs. It would (at present) be too costly to make individual puzzles by these processes, but the economics could change in a decade. Whether it is possible to pour melted plastic into molds to make the pieces of a Cube-like puzzle is at present very doubtful, but it might be, in the future. (Rattlebacks, also known as celts, look just like solidified poured plastic.) It's unfortunate that the economics that make possible the affordable production of large numbers of such puzzles as the 4^3 also mean that starting another production run has to be economically justified. Let's hope that the tooling for manufacturing such miracles as the 5^3 and the Magic Dodecahedron is preserved! Failing that, at least any CAD files for doing numerical machining of the molding dies really ought to be kept and backed up. Hope I'm not too far off-topic. {"afaik" = "as far as I know", pointed out as a courtesy to non-native users of English} {END of the text I posted to the wrong List -nb} * * * {The following replies are posted with the gracious permission of their respective authors. } Here's a reply from Javier Susaeta: Yes, I have read a bit about rapid prototyping and believe that it has a tremendous potential. I cannot tell you where I read it, but I remember a case where a complete intake manifold was designed by CAD/CAM and then a single copy was (slowly) built, layer by layer, with one of the just-born rapid-prototyping machines. The material used was aluminium powder plus a plastic agglomerant. Once the manifold was "finished" it was baked in an oven in order to eliminate the agglomerant and weld together the metal particles. The result was not so solid as a cast aluminium manifold, but nevertheless perfectly usable. (Referring to more details, Javier said:) I remember having read it in internet, a few months ago. The intake manifold was for a specially-built big diesel of a bulldozer or a similar machine. I am not sure, but perhaps it was from Caterpillar or a similar US company. They resorted to rapid prototyping because of costs. It was a very special engine, and they needed 1 (yes, one) intake manifold. The fixed costs for a single casting were enormous, and a manifold is so convoluted that machining it out of a block of metal was impossible. So they resorted to this new technique. Regards Javier Susaeta Here's some more on the topic, from Mark Glusker: Date: Sun, 27 Jul 1997 14:33:36 -0700 (PDT)