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 Post subject: Skewb's Mechanism?
PostPosted: Thu Aug 30, 2001 1:44 am 
Can someone explain to me, in some detail, how the skewb is built? I want to mold a puzzle with the same mechanism, but I need to know it first.

Horrorkid


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 Post subject: Skewb's mechanism.
PostPosted: Thu Aug 30, 2001 2:08 am 
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Location: Canada
The Skewb is based on a tetrahedral mechanism. 4 of the corners are fixed in place, while the other 4 are "floaters". To see the mechanism for yourself, simply rotate one side of the puzzle by 60 degrees so that you have centres beside centres and corners beside corners. Then pull the corners away from each other and the puzzle should fall apart without much effort. L8r.


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 Post subject: Untitled
PostPosted: Thu Aug 30, 2001 6:30 am 
Thanks!
Do you know how the fisher's cube works? I have the materials to mold plastics, but I don't have a fisher's cube or any idea of how it would work. If I had some idea of it, I could probably duplicate it.
Horrorkid


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 Post subject: I think I know
PostPosted: Thu Aug 30, 2001 8:46 am 
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Im fairly sure this is right...

I believe it is just a 3x3x3 modification.

The pieces that are the corners on a Fischer cube (FC) were originally the edge pieces on the regular cube (RC). They have had some extra plastic stuck onto them to make them stick out. The pieces that are the edge pieces on the FC were originally the corners on the RC. They have been shaved down a bit in order to match up to the new edges.

Actually, have a look at the puzzle in Wayne's wanted list called "Star cube (3x3x3 variation)". It should be clear how to make this one. Then just shave down the corners until it looks like a cube again.

Hope this helps.

-James.


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 Post subject: Or rather...
PostPosted: Thu Aug 30, 2001 3:22 pm 
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Location: Palerang Shire, NSW, Australia
A better way of thinking of it is actually a variation of the octagon variation. That way, the only difference is that the edges stick out, and the centres stick out.


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 Post subject: Yeah thats clever.
PostPosted: Thu Aug 30, 2001 11:04 pm 
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I guess you could take half of the octagon's pieces (the 'corners') and half of the star cube's pieces (the 'edges') and make one.

I havent ever held either of these puzzles so maybe thats why I didnt make the conection. :wink:


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 Post subject: Cheap and easier
PostPosted: Fri Aug 31, 2001 8:49 am 
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Location: Palerang Shire, NSW, Australia
You're much better off in the long run to simply buy skewbs and make the pieces you need from it or adapt them using plastic resin.

Believe me, after casting 10 or 11 common axis pieces you'll soon get sick of it and find it time consuming.

Why re-invent the wheel for yourself. Anyway, see how you go.


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 Post subject: Fischer and Star cubes
PostPosted: Fri Aug 31, 2001 1:13 pm 
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Joined: Tue Mar 14, 2000 9:11 pm
Location: Dubuque, IA area
Actually, I think (I'm not 100% sure) that the Star cube was made from a regular 3x3x3 cube with parts from a Fischer cube; that is, I think the Fischer cube came first, before the star cube. Perhaps Tony Fischer made the star cube himself. If anybody has contact with Tony Fischer, we could probably confirm this. I have also heard that there was less than 100 Fischer cubes ever made (at least by Tony Fischer). Unfortunately, I do not own one of them. Does anyone know how Tony made his creations? Are they specially molded parts or are they parts from common puzzles that have been cut to remove features and glued with pieces to add features?

Doug.


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 Post subject: Is this safe?
PostPosted: Sun Sep 02, 2001 4:38 am 
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You gave some instructions on how to disassemble a skewb. I love my skewb! Is it safe to pull it apart? Would I be able to put it back together again with no problems?

-James.


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 Post subject: Fisher and Star Cubes
PostPosted: Sun Sep 02, 2001 7:43 am 
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Joined: Tue Jul 25, 2000 2:35 am
Location: Oshawa Ontario Canada
There's no 'c' in Tony's last name.

Mr. Fisher has already stated he's working on new designs, and after making only 4 Fisher Cubes I can point out a couple of interesting things.

There were quite a few size variations with the octagon (aka space shuttle) puzzle. One was actually slightly larger than cube size, and one was slightly smaller :) When I say cube size, I mean 57 mm, but even with the normal 3x3x3 cubes they are usually just under 57 mm, more like 56.5 mm.

There's also a 45 mm one floating around from China which is real junk.

When working with these different puzzles I noticed that even if one part was 1 mm different in size, it was noticeable. Sometimes this is only noticeable when I combined pieces from different puzzles. The upshot of all this was I learned it was better to make a good mold for every size, even if you're not making the whole thing from stratch, since then you'll be ready if you get a puzzle if slightly different size.

I can say one thing, I've learned from experience, and that's try, try again :) Even experienced mold makers have a bit of trouble making a good mold for the more complex cube pieces but it is possible to make a fully functional twisty puzzle without fancy stuff like CNC machines, and injection molding and ABS plastic. The pieces won't be as accurate, but they will work.

I'll predict in 5 years, 10 years at most, all the prototypes of cube type puzzles will be made. The technology and access to the technology will get better and better.


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 Post subject: Is it safe?
PostPosted: Mon Sep 03, 2001 4:38 am 
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Location: Canada
Indeed it is. I've dismantled and reassembled by Skewb many times with no problems. In fact, I'd say it's one of the easiest and safest puzzles to dismantle and reassemble, period. L8r.


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 Post subject: Execution of New Puzzle Designs
PostPosted: Mon Sep 03, 2001 7:48 am 
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Joined: Sat Dec 02, 2000 8:27 pm
Location: Wilmington, NC, USA
Mark, I sincerely hope your prediction comes true:

"I'll predict in 5 years, 10 years at most, all the prototypes of cube type puzzles will be made. The technology and access to the technology will get better and better."

There is such a fantastic selection of virtual designs out there. One of my personal favorite sites for these ideas is David Byrden's site (thank you, Mark, for the link from your homepage):

http://Byrden.com/puzzles/MainFrames.html

I can't wait to see these executed as physical puzzles!


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 Post subject: I wouldn't say it's junk...
PostPosted: Mon Sep 03, 2001 11:17 am 
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Location: Palerang Shire, NSW, Australia
I picked up a 45mm cube yesterday and to my surprise, the cubies are almost the same size as the ones in the 4x4x4 cube. Therefore the tiles from two of these would make perfect replacement tiles for an oddzon 4x4x4 cube...


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 Post subject: How about 7x7x7 cubes or 3x3x3x3 cubes (4th dimension)?
PostPosted: Mon Sep 03, 2001 4:24 pm 
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Joined: Tue Mar 14, 2000 9:11 pm
Location: Dubuque, IA area
I'm assuming that Mark means all practical puzzles. The larger size cubes (7x7x7, 8x8x8, etc.) probably won't be possible. Also, puzzles that use a fourth dimension like a 3x3x3x3 cube would also be quite difficult to develop. Lucky for us, we have computers to make virtual puzzles like on Byrden's site.

Doug.


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 Post subject: 45mm cubes
PostPosted: Tue Sep 04, 2001 11:17 am 
Does anyone know of a source in the USA or on the net for 45mm cubes? I have an old beat up one and it is one of my favorites. I would like to get some new ones.

-Chris


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 Post subject: Prototype vs. Production Puzzles
PostPosted: Wed Sep 05, 2001 4:12 am 
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Joined: Tue Mar 14, 2000 9:11 pm
Location: Dubuque, IA area
Keep in mind that Mark states "prototype", not "production", puzzles. The tooling costs to bring a puzzle to production is typically quite expensive and requires a lot of sales to pay it off. But, with processes like SLA (stereolithography) and "slush" (RTV silicon) molds, it is quite realistic to make a handful of prototypes. Still, the per puzzle cost for these prototypes will be expensive, but it may be worth it to have a truly unique, rare puzzle in one's collection.

Doug.


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 Post subject: Clarification
PostPosted: Wed Sep 05, 2001 7:59 am 
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Joined: Tue Jul 25, 2000 2:35 am
Location: Oshawa Ontario Canada
I'll be more specific...

when I said "all prototypes will be made", I was mainly refering to Meffert's cardboard mockups which were written about in Scientific American back in 1982. Uwe Meffert also published a colour booklet titled "The New Exciting 1982 Range: Pyraminx". A large number of those puzzles didn't go beyond the cardboard mockup stage. There was rumours of a company in the Netherlands that actually made quite a few of these, but details are sketchy. Examples of what I'd like to see made are the Pyraminx Hexagon, Pyraminx Pentagon, and a face turning tetrahedron.

The Pyraminx Cube (Skewb) and the Pyraminx Magic Octahedron (same puzzle Wayne duplicated) obviously exist. The Pyraminx Ball (aka Ultimate Skewb) are recent additions. I don't see any big problem making Dino Cubes, but the Master Pyraminx is a different story. I don't think there is any mechanism for it, as yet. And as many people know, lots of room for improvement on the original Rubik's Domino design, or at least it's construction.

The main problem with making certain 3x3x3 cube modifications is intermixing parts from different puzzles don't always fit together well.

One item I'd like to get is a white Logical Games cube. Logical Games brought the cube to North America before Ideal Toy bought the exclusive rights. It would be interesting to see if mechanism was the same.


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 Post subject: Whoa! Nice! :-)
PostPosted: Thu Sep 06, 2001 6:38 am 
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Any idea where to get one of these setups and how much they'd cost, Doug? L8r.


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 Post subject: A Gallery of Pieces
PostPosted: Thu Sep 06, 2001 7:59 am 
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Location: San Francisco, CA
Given Meffert's assembly cubes (and the cheap and apparently identical and probably patent infringing knock-offs) as a base, it would be nice to assemble a gallery of conforming variation pieces from which to put together the known variations of the 3x3x3.

For example:

Edge pieces
- ridged (like the Trabjer's Octahedron)
- peaked (like the Star & Fisher cubes)
- partially truncated (like the 14-sided Diamond/Octaeder)

Corner pieces
- shaved (like the octagon or Fisher cube)
- shallow truncation (like the Truncated Cube)
- deeper truncation (like the 14-sided Diamond/Octaeder)
- deepest truncation (like the 26-sided Diamond, or Trajber's Octahedron)
- degenerate (just the foot)

Center caps
- peaked (like the Trajber's Octahedron)

Etc. There are several others - e.g. components of the Sphere, or the 12-sided diamond, or bandaged/siamese variants, or ...


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 Post subject: Prototyping methods
PostPosted: Thu Sep 06, 2001 8:59 am 
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Joined: Tue Mar 14, 2000 9:11 pm
Location: Dubuque, IA area
You can get a SLA (stereolithography) machine for about $500,000. There are also places that have the SLA machine which will make the pieces for you when you send them a CAD model of your part, but the parts aren't cheap either. I would guess that it would cost about $200.00 to make one corner piece to a standard 3x3x3 Rubik's cube. Keep in mind, however, that the plastics which are used with stereolithography are limited. They typically have poor strength and chemical and wear resistance. We sometimes use this service to make prototypes to evaluate a part's fit with other components where I work.

The slush mold technology is relatively simple and cheap. Wayne's "working with plastics" page gives the basics.

Doug.


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 Post subject: Stereolithography
PostPosted: Thu Sep 06, 2001 12:33 pm 
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Location: Oshawa Ontario Canada
Thanks Doug, I was wondering if stereolithography
was practical for making cube parts.

I believe in the toy industry the usual practise is to use CNC machines to make molds from aluminium or steel, then they use injection molding machines with heated ABS resin. I think one could buy a small CNC machine which could cut aluminium for about $5K, but it would certainly take a bit of practise to program a machine to mill a mold. This would certainly be a lot more durable than using rubber molds.

Even after you make a decent mold there is the casting to consider. As you point out, to produce a functional puzzle the pieces have to be fairly strong. My experiences with polyester resin showed me that it isn't the greatest material for this sort of thing. When I tried to pop in the polyester resin part, it actually felt like it was giving too much. It did function, but it looked very rough. I always got a lot of air bubbles, even on the outside surfaces.

I've found that most pros that do their own casting use polyurethane resin, and both Wayne and I agree it's tons better. Polyester resin is cheaper to buy and colours easily. Polyurethane likes to be white.
But the strength of the polyurethane is much better, plus air bubbles are far less of a problem.

It would be better still to cast under pressure. The usual amount I hear is 100 PSI, but probably less would do. Also before anyone runs out and buys 5 gallons of polyurethane resin I should point out this stuff as a pretty short shelf life. You can buy extender products to keep it from aging as quickly.

I don't see people modeling these types of parts from clay, but I guess it's not impossible. I'd much rather use some type of CAM software and have a machine do it. Making completely new mechanisms is going to be the real trick.


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 Post subject: Clay - Milliput
PostPosted: Sat Sep 08, 2001 4:38 pm 
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Location: Delft, the Netherlands
> I don't see people modeling these types of parts
> from clay, but I guess it's not impossible.

Does anyone else have some experience with milliput ( http://www.milliput.com ). It is a type of 2-component epoxy putty that becomes rockhard in a couple of hours.

I've used it a little. I have a few spare puzzle balls (i.e. skewbs) and used the putty to build up the pieces into different shapes. I made an Ultimate Skewb, as well as a rhombic dodecahedron that way.

Theoretically it may be possible to use the stuff to make moulds, as well as use it to make pieces from with those moulds. Has anyone tried this out?


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 Post subject: Milliput
PostPosted: Sun Sep 09, 2001 4:38 pm 
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Location: Palerang Shire, NSW, Australia
I think I have some of this. A friend gave it to me, but I never used it. How nice did the pieces turn out with it? How did you mold it smooth? Were the pieces kind of rough and amatuer?


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