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 Post subject: Hex Crystal and Hex Nut
PostPosted: Thu Feb 09, 2012 11:59 pm 
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After setting on the idea for quite some time, I have finally finished my first 3D Printed Puzzle. I call it the Hex Crystal due to its crystalline shape. Mechanically, it is the 3-Layer counterpart of the Rubik's Cheese and Rubik's UFO. The shape is something I have dubbed a Golden Elongated Hexagonal Dipyramid, golden referring to the fact that its faces are golden triangles and golden rectangles.

Before I get to the pictures, I would like talk about the history of my design:

I first hinted at this puzzle in May of 2010 when I posted the following in Hints of Secret Ideas:
Jeffery Mewtamer wrote:
12 Golden Triangles and 6 Golden Rectangles.
3-Layer version of a mass-produced puzzle.

At that time, I just had the idea: The shape and how it would turn.

In May 2011, I followed up with this more detailed hint:
Jeffery Mewtamer wrote:
12 Golden Triangles
6 Golden Rectangles
Mass-produced core
3-D printed shell
~$240 in printing costs without hollows.
Design complete, just need to hollow to make it prototyping affordable.

This post was based on a V1 design that I never had printed. It was much larger(short edge length of 4cm) and used the core from a Rubik's UFO. Even hallowed, it was still too expensive for my liking to print, and the UFO becoming harder to come by cheaply only added to the price. So I decided to scrap the design and make the V2 design have its own core.

I finally printed V2 in November of 2011, but could not produce a working prototype as the grooves in the center layer were too narrow for the feet of the outer layers to fit. I was however, able to make a shapemodded Cheese from the throwaways that I have dubbed the Hex Nut. I made a V2.1 revision to fix the fitting between center and outer layers, and I also made the core looser fitting for easier assembly/disassembly. The prototype displayed below uses the V2.1 Core and Center Layer with the V2 Outer Layers, which I did not modify.

Anyways, here are the pictures of the Hex Crystal:
Attachment:
File comment: Hex Crystal view 1
Hex Crystal.png
Hex Crystal.png [ 181.79 KiB | Viewed 1870 times ]

Attachment:
File comment: Hex Crystal view 2
Hex Crystal 2.png
Hex Crystal 2.png [ 184.45 KiB | Viewed 1870 times ]

Attachment:
File comment: Hex Crystal turning on a deep cut.
Big Turn.png
Big Turn.png [ 267.23 KiB | Viewed 1870 times ]

Attachment:
File comment: Hex Crystal turning on its shallow cuts.
Small Turn.png
Small Turn.png [ 220.05 KiB | Viewed 1870 times ]

Attachment:
File comment: Hex Crystal scrambled
Hex Crystal Scambled.png
Hex Crystal Scambled.png [ 180.93 KiB | Viewed 1870 times ]

And of the Hex Nut:
Attachment:
File comment: Hex Nut WSF
Hex Nut.png
Hex Nut.png [ 928.98 KiB | Viewed 1870 times ]

Attachment:
File comment: Hex Nut Colored
Hex Nut Colored.png
Hex Nut Colored.png [ 120.93 KiB | Viewed 1870 times ]

As you can see, I chose to go with colored plastic for finishing my prototypes. I chose this as I felt custom stickers would be cost prohibitive for such a small puzzle and the fact that classic cheeses use the same kind of finish. I chose to use Sharpie instead of dye as it seem the cheaper and easier option. For some reason, even though the parts were coloered at the same time, the Hex Nut remains vibrant while the Hex Crystal has gotten dull and dingy.

Turning wise: The Hex Nut, using the tighter fitting V2 core turns smooth as smoothly, on par with some of the mass produced puzzles in my collection. The Hex Nut can even cut corners. On the Hex Crystal, the tips turn quite well after breaking in, though they still catch from time to time. The turns along the puzzle's length tend to go easily if everything is lined-up, but catch if the tips are out of alignment.

I would like offer this puzzle on Shapeways, but I want to get public opinion to ensure my design is unique enough before I make the model public. Also, I feel like the core needs at least one more revision: The V2 core, which is designed to fit snuggly with the stems on the puzzle's centers makes the puzzle difficult to assembly and disassemble, but makes for a very stable puzzle once assembled(as the Hex Nut shows). The V2.1 core which has a small gap(~1 mm) between itself and the center stems makes for easy assembly, but results in a very loose puzzle as the following image shows:
Attachment:
File comment: That gap is entirely due to looseness, and stayed open long enough for me to take the photo.
Gap.png
Gap.png [ 46.68 KiB | Viewed 1870 times ]

Assembling the Hex Crystal with the V2 core proved impossible, and using one of half of each core produced tighter build, but more catches in Cheese turns. I am thinking a V2.2 core that is halfway between the previous revisions might be the best.

For those interested, here are the measurements:

Edge Lengths:
Short: 20mm
Long: 32.36mm or ~20phi mm

Hexagon Cross-section:
In-radius: 17.32mm or ~10sqrt(3)mm
Out-radius: 20 mm

Total Length: ~83.24mm or ~2sqrt((20phi)^2 - 20^2) + 20phi

Weight: Unknown as I lack an appropriate scale, but the above should be enough to calculate total volume and the pieces are solid and the puzzle has negligible cavities.

Also: no hardware required for assembly.

Mechanism pictures:
Attachment:
File comment: Center layer and core
Parts1.png
Parts1.png [ 1002.5 KiB | Viewed 1870 times ]

Attachment:
File comment: Outer layers
Parts2.png
Parts2.png [ 1.83 MiB | Viewed 1870 times ]

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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Fri Feb 10, 2012 11:04 am 
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Location: Koblenz, Germany
When I saw the first image I thought the puzzle is made from wood.


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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Sat Feb 11, 2012 9:30 pm 
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Joined: Sun Nov 23, 2008 2:18 am
Andreas Nortmann wrote:
When I saw the first image I thought the puzzle is made from wood.


I wish I had the craftsmanship to make something like this out of wood(if I did, I might have actually made more progress on the hand made side of things other than a few unfinished 3x3x3 and 4x4x4 mods).

Also, I forgot to include a size comparison, so here is the Hex Crystal and Hex Nut with the Jewel Pyraminx:
Attachment:
File comment: Size Comparison
Size Comparison.png
Size Comparison.png [ 679.27 KiB | Viewed 1541 times ]

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I pledge allegiance to the whole of humanity, and to the world in which we live: one people under the heavens, indivisible, with Liberty and Equality for all.

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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Sun Feb 12, 2012 3:40 pm 
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Joined: Wed Jan 07, 2009 6:46 pm
Location: Evanston, IL
Cool puzzle.
Jeffery Mewtamer wrote:
the pieces are solid and the puzzle has negligible cavities.
That's why such a small puzzle cost $240. You really should hollow out the parts before trying to offer it on Shapeways. What CAD program are you using?

Also, you should consider dying the puzzle next time. While sharpie might seem like a good alternative, the oil in your fingers will eventually make the colors bleed and the ink will dye your fingers.

-Eitan

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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Sun Feb 12, 2012 7:25 pm 
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Joined: Sat Mar 22, 2003 9:11 am
Location: Marin, CA
I wonder if there's a way to make a two-layer hexagonal prism where it's only possible to slice the big axis 180 degrees.


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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Sun Feb 12, 2012 10:57 pm 
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Joined: Sun Nov 23, 2008 2:18 am
The $240 Figure was based on the older design that used the core from a Rubik's UFO and was much larger(40 mm versus 20 mm for the shorter edge length). The current design is about $50 for a full print in WSF.

The Hex Crystal was designed using FreeCAD. With the version I have, hollowing parts can only be done in a around about way via the Python console.

_________________
Just so you know, I am blind.

I pledge allegiance to the whole of humanity, and to the world in which we live: one people under the heavens, indivisible, with Liberty and Equality for all.

My Shapeways Shop


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 Post subject: Re: Hex Crystal and Hex Nut
PostPosted: Mon Feb 13, 2012 3:04 am 
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Joined: Sat Mar 29, 2008 12:55 am
Location: WA, USA
Bram wrote:
I wonder if there's a way to make a two-layer hexagonal prism where it's only possible to slice the big axis 180 degrees.


Wouldn't that make the puzzle trivial?

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