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 Post subject: Half turn cube?
PostPosted: Thu Feb 20, 2003 1:22 am 
I've been trying to figure out a way to produce a cube that is restricted to half twists. I think this would be an interesting puzzle in it's own right, but would also make some variations (eg Wayne's half trunc cube) retain shape.

Anyone thought about a way to do this, all ideas I come up with work by adding plastic to jam subsequent twists if a half twist is made. I'm not sure if these additions would hold up. Is there another way I am overlooking.

Max


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 Post subject: Re: Half turn cube?
PostPosted: Fri Feb 21, 2003 1:47 pm 
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Joined: Wed Mar 15, 2000 9:11 pm
Location: Delft, the Netherlands
MaxWiz wrote:
> I've been trying to figure out a way to produce
> a cube that is restricted to half
> twists.

There is no kind of bandaging/gluing of pieces that will do the trick. The only thing I can think of is by making the three centre slices have differing thicknesses. You could for example sand down one middle slice by say 2mm on either side, and build up the adjacent slices by the same amount. Do a similar thing on a differnt middle slice but in the opposite direction, i.e. buld up the middle slice and sand down the adjacent slices.

I think 2 mm should be enough to overcome the springiness, but if not then you could always tighten it or use an assembly cube instead.

Of course, the way I have described it here, the difference in thickness is visible on the outside. It should be possible to do this on the inside only, by sanding down/building up only a circular groove or disc on the internal faces, or even by extending/cutting back the feet of the pieces.


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 Post subject: Re: Half turn cube?
PostPosted: Fri Feb 21, 2003 4:30 pm 
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Doesn't a 3X4X5 or any cube that has all different dimensions allow only half turns? I gues you could then bandage it to make a 3X3X3. That sound like a new idea for you builders!


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 Post subject: Re: Half turn cube?
PostPosted: Sat Feb 22, 2003 2:02 am 
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It would probably be easier to do what max said than to make a cuboid just to modify it further


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 Post subject: Re: Half turn cube?
PostPosted: Sat Feb 22, 2003 9:04 am 
Thanks Jaap, I think that does it. Might have a go with a cheap medium sized cube, so if it does work I can put it in a regular one, a la Fisher's transforms. So could use bigger differences eg 4mm instead of 2.

Max


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 Post subject: Re: Half turn cube?
PostPosted: Sat Feb 22, 2003 4:30 pm 
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It would probably be easier to do what max said than to make a cuboid just to modify it further


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 Post subject: Re: Half turn cube?
PostPosted: Sun Feb 23, 2003 2:02 am 
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Oh, Jaap said it. Oops


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 Post subject: Re: Half turn cube?
PostPosted: Tue Mar 11, 2003 12:15 pm 
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Joined: Wed Nov 24, 1999 12:18 pm
Location: Palerang Shire, NSW, Australia
I understand a half turn cube to be one that you can turn each face 45 degrees. I tried to model of these but it didn't work out. There turned out to be too many "holes" or gaps, and the cubies ended up being cubohedrons. Also, it seemed to be too flimsay. Maybe it's workth having another look at...


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 Post subject: Re: Half turn cube?
PostPosted: Tue Mar 11, 2003 7:32 pm 
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Joined: Tue Mar 14, 2000 9:11 pm
Location: Dubuque, IA area
I'm not sure but I think that they are talking about 180 degrees turns, where 90 degrees turns are not allowed. Is this correct, anyone?

Doug.


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 Post subject: Re: Half turn cube?
PostPosted: Wed Mar 12, 2003 3:17 pm 
Thats what I meant.

Max


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 Post subject: Re: Half turn cube?
PostPosted: Wed Mar 12, 2003 3:31 pm 
The half turn cube does makes for an interesting puzzle. I did this a while ago using normal cubes, mixing it up using only half-twists, and then trying to solve it using only half-twists. The 2x2x2 is pretty trivial to solve this way, but 3x3x3 (or more) can become surprisingly difficult. The part that can be maddening, is that it's not too hard to reach positions that are very close to solved if quarter-twists were allowed.

I find it aesthetically pleasing how each side and its opposite are always a combination of the same two colors.


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 Post subject: Re: Half turn cube?
PostPosted: Wed Mar 26, 2003 3:26 pm 
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> I find it aesthetically pleasing how each side and its
> opposite are always a combination of the same two colors.

Hmm, you could colour the whole puzzle with just two colours, without losing any solving difficulty. In fact, it would probably throw people off somewhat!


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 Post subject: Re: Half turn cube?
PostPosted: Thu Mar 27, 2003 3:26 pm 
If using two colors, it might look neat to use a round shape (like Rubik's World), with each hemisphere having it's own color. I envision the dividing line between hemisheres to be such that each half completely contains three "centers" of its color.

Black and white (or light gray) could be used to go with a lunar theme! This could include stickers showing craters, or possibly the pieces could actually be shaped with bumps.

This Moon theme could be used for other round shapes too, like something skewb-based, or maybe a Rubik's UFO shaped into a sphere.


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