Vacation is wonderful! My dad came for a visit, and he helped me make an octaminx. Here's the link to photos and construction notes:

http://home.ec.rr.com/specialpuzzles/Index.htm

Anyone have suggestions for the next custom puzzle?

It really looks sharp. Good job.

Its beautiful!!

Did you continue to use springs between the machine screws and the faces to keep tension on the puzzle, or dispense with them? If so, how deeply did you cut holes into the faces for the springs to sit and how long were the springs? If not, how well does the puzzle function?

(I've got a half-completed Octaminx on my desk, which is held together by the original screws and springs so it looks like a strange satellite.)

We omitted the springs. We still have the little click balls, and we adjusted the screws to provide comfortable tension. I don't believe you could build this puzzle with the springs unless you sunk the screw holes a lot deeper and cut the springs very short.

Nice job!

I modelled an octaminx in blender from a tetraminx. Is there any reason you used a pyraminx instead of a tetraminx?

I've been sitting here for a few days with a tetraminx in front of me trying to visualize it . Starting with a tetraminx, do you cut farther into the puzzle? How big are the middle triangles of the Octaminx in relation with the middle triangles of the tetraminx, the same size? I'm having trouble visualizing the side where the middle is solid...

If you cut the tips off the pyraminx, you get the tetraminx. If you cut slightly deeper, so that the cutting planes just meet at the edges, you get the octaminx. The cut

There are versions of the rubik's cube where the corners have been cut down until these triangular cutting planes just meet at the edges. This give a 14-sided shape, the cuboctahedron. The cut planes show a hexagon from the corner piece, and 3 small triangular facelets from the adjacent edges.

The octaminx similarly has hexagonal facelets at the cut planes with three small triangular facelets from the adjacent edges. See this pic:



Jaap

I'd like to make one... I have an extra pyraminx. but, i cant see how you make it. can anyone help?

Tyler, set your pyraminx in front of you flat on the table with a face toward you. Draw an imaginary line from halfway down the outside edge of one edge piece to halfway down another outside edge of one edge piece. If you cut along that line and did so for every side, you will have the octaminx. The middle triangles are quite a bit smaller than the middle triangles of the pyraminx even though they correspond exactly. hope this helps

Jaap, do you know if anyone has attempted to build the 3x3x3/tetrahedron alluded to on your site?

That is, remove 4 corners from a 3x3x3 cube and treat each as one "face" of a tetrahedron, then shave down/build up the cube until it is a full tetrahedron. Four corners of the original cube and three adjacent edges get cut down even further than a cuboctahedron to form the faces; the other four corners, face centers, and the edges get built up to form the edges.

As you mention, it will change shape if you make quarter turns, which raises these interesting questions:

- Is there a simple tweak to the 3x3x3 mechanism to restrict it to half turns?

- If you allow quarter turns it would take on some dangerous looking shapes. This might be cool. But if you scramble the puzzle using quarter turns, then return it to a tetrahedral shape but unsolved (like the common Square-1 algorithms), can you then solve it using only half-turns? If not, can you easily determine you're in this state by inspecting the puzzle?

(The latter could be answered by analyzing a four-color sticker pattern on a 3x3x3, with no need of knives or putty. But that's no fun.)

Joshua,

I think it is called the Master Pyraminx, or Senior Pyraminx (I always get these mixed up). Meffert designed mechanisms and probably made prototypes, but I don't think it was ever really made. He designed some kind of locking system to keep the tips from falling off midway through a turn.

> As you mention, it will change shape if you make quarter turns

Actually, it will definitely fall apart if you allow all quarter turns. You could swap a corner pieces with a missing corner, and it would no longer be attached.

> Is there a simple tweak to the 3x3x3 mechanism to restrict it to half turns?

I don't know. You can theoretically make a cube mechanism that is scaled differently along the three axes. For example, you could make the middle slices have all different widths, leaving the internal mechanism the same. Alternatively, you can make the internal mechanism oblong, leaving the outside cubies looking the same. Right now I can't think of an easy way to achieve this, but I think there probably is some quick hack method for it.

> But if you scramble the puzzle using quarter turns, then return it to a tetrahedral shape but unsolved (like the common Square-1 algorithms), can you then solve it using only half-turns? If not, can you easily determine you're in this state by inspecting the puzzle?

As I said, this puzzle with quarter turns cannot possibly work in real life, but it might make a neat computer simulation.

If it is in tetrahedral shape, the only restrictions you have made is (using cube terminology) that the flip of all the edges is determined, the four corners are in the four corner positions (possibly permuted), and the centres need only half twists.

For it to be solvable in half turns, you would also need the edges to be in the correct slices, the edges to be in an even permutation, the corners to be correctly oriented, and the corners to be permuted only by double swaps (not by 3-cycles). I'm not sure if an odd number of flipped face centres is possible.

Jaap

Sounds good...
The 2 edges are on adjacent sides, right?
If so, i now know how to do it.
Thanks

In making the octaminx, it occured to me that this would be a superb puzzle if it was a bit larger. I then realized that I have never seen a large (in size) pyraminx. did they ever make them? I have seen keychain ones but never one larger. boy, the keychain would make a tiny octaminx...

I don't think we're talking about the same puzzle. I'm not talking about an Master Pyraminx, but a regular old 3x3x3 cube that's been built up to be shaped like a tetrahedron.

On your site...

>>>>>>>>
Puzzles with 6 axes of rotation

Tetrahedron

A tetrahedron does not have cube symmetry, so if we embed a cube mechanism inside it will change shape unless only half turns are allowed.

One variation already exists, the Pyramorphix. It is a tetrahedron with two pieces to an edge, and as such is based on a 2×2×2 Rubik's cube mechanism. The only difference between them is that this time the orientations of four of the pieces do not matter.

A version with three pieces to an edge would be an interesting one. It would be like a Rubik's cube with four corners missing, but where orientation of the face centres matter, and only half turns are allowed.
<<<<<<<<

The same puzzle can be achieved with a 4-coloring pattern on a 3x3x3 (like the 4-color Dino cube coloring). I don't see any problem with converting a cube into this shape - why would the corners fall off?

So you mean something like how 2x2x2 --> Pyramorphix ?
Except with a 3x3?

I started last night hacking away at my tetraminx. I measured the halfway mark of the outside edge of the edge pieces and then drew lines connecting each adjacent marks. (the drawn lines make triangles on each side) I then sawed the puzzle along the lines. The edge pieces make the corners of the octaminx and vice versa. I had to use a drill to lower the screw holes to get them below the surface of the new puzzle. I used screws from an old 3x3x3 cube and they were the perfect fit. I had to cut the original springs from the tetraminx down and add them to the puzzle to make it feel right. Right now, after about 10 anti-clockwise turns the puzzle falls apart because a screw comes loose. I suppose I'll have to find a small washer to keep this from happening. Does anyone know any other way to fix this?

It needs some serious sanding and maybe some touch up with some Milliput. The puzzle is MUCH smaller than I first envisioned. Once I fix the turning problem, it will be easy to sand everything down and then resticker. Is this puzzle any harder than the pyraminx?

Yes, that is what we're talking about now.

I just saw it, so this puzzle is a very much cut down version and is quite a bit smaller than the pyraminx from which it was altered. I was trying in my mind to make the three triangle pieces be the exact size as the ones on the pyraminx/tetraminx. thanks, I'll have to make one now....

i started cutting also.
I did about half of it.
Im going to need a massive milliput buildup - i cut too far on one side

What brand of pyraminx did you start with?

I've seen at least two different sizes for a Pyraminx. I believe that the original was about 4" in height. Up until I bought an original Tomy a few months ago, I had imagined they were all the same size as the key chain-sized one I had when I was a kid. I was shocked to see how large the Tomy was.

A few days ago, I received another one in the mail, it says Meffert on the top yellow logo sticker, but it seems to be otherwise exactly the same as the Tomy. Here it is:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1713237986

UNRELATED - Doug almost sniped me out of the following item while I was writing this message! Just when I thought I was going to get it for $5.50! Anyway, does anyone know what the difference is between a Morphinx and a Tetraminx?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1716442702

Sandy

Yes, we are talking about the same puzzle. Meffert designed a pyraminx where instead of the corners turning, the edges rotate 180 degrees. This is essentially the rubik's cube cut down to tetrahedral shape and resticted to half turns. Meffert also designed one that allows both types of move - edges and corners. One of these is the Senior, the other the Master Pyraminx.

> The same puzzle can be achieved with a 4-coloring pattern on a 3x3x3 (like the 4-color Dino cube coloring).

Not quite. That has four monochrome corner pieces that do not exist on the tetrahedron. If you remove them, you get the equivalent puzzle.

> I don't see any problem with converting a cube into this shape - why would the corners fall off?

The cube edges have been flattened so much that they only hold on to a corner piece on one side. Turning one 'face', the corners overhang completely on one side after a quarter turn. Now turn one of the other 'faces' that contain that corner. It will now overhang on two sides...

If you have a corner with all three adjacent edge pieces flipped the wrong way, there is nothing to hold it. This occurs for example if you swap a real corner of the cube with the missing one on the diagonally opposite side of the 'cube'. You would have a corner piece hanging off in space with a seemingly solved tetrahedron face underneath it.

You could hovewer still make the puzzle as long as you sacrifice something, e.g. make it bulge in the middle, allowing a small space in the centre of the solved faces where a corner can connect to the mechanism.

Jaap

Sounds like a cool puzzle...
my idea for making something liek this (tetrahedronal 3x3x3 would have extensions of at most 1.5 inches
Sounds like a good project...

What can i use to sand down milliput? Sandpaper? or do i need an electric?

If you don't try and cut all of the pieces down there shouldn't be a problem with the corners - but you do end up with irregular face shapes and sizes. I took a first stab at it with a mini-3x3x3. Here are the cut-down corners:



And here is some early build-up on three of the twelve edge pieces:



And a "mockup" of what a finished face would look like:



And a drawing of the complete puzzle:



The tips wouldn't turn, only the edges - exactly as in the Master Pyraminx, as you say. Still, this might be worth building.

Heck, this could even be marketed (okay, to a limited audience) as a puzzle with two levels of complexity. First level: half turns only. Second level: any turns allowed.

The real challenge might be naming it.

Carter, what brand of Pyraminx did you start with? New Mefferts, old Mefferts, Tomy, or other? I never realized that the Pyraminx center pieces were solid plastic. Who would have thought? Does anybody know if this is true for all Pyraminxes?

Doug.

Official mefferts

Joshua, you have explained a puzzle that I've been pondering on the 3D Puzzle Reconstruction Studio:

http://csx.jp/~3dpuzzle/index.html

I have not been able to figure out how to build it. Your photos explain it perfectly. Great job.

I think all pyraminx/tetraminxes have the same size, except for the smaller keychain ones. There is however a knock-off version that has a rounder shape, like the top-right one in this picture:


I last saw one when I was 10 or 11 years old, but in my memory it was slightly larger than an official pyraminx. As I was smaller myself, this was probably not really the case.

> it says Meffert on the top yellow logo sticker, but it seems to be otherwise exactly the same as the Tomy.

I still have an original Tomy one, without the Meffert sticker but on the black base of the casing it does have a Meffert copyright.

> does anyone know what the difference is between a Morphinx and a Tetraminx?

Looks like a normal Meffert tiled Tetraminx to me. Never heard of the name Morphinx before, and it is probably a mistake by the ebay seller. One puzzle on ebay that seems to have lots of different names is the tricky disky. I've seen it called Mind Bender, Ufo, and other names.

Jaap

This would be a lot of pieces to make. The best approach might be to sculpt a face then replicate by molding.

Re: Names - the reconstruction site doesn't seem to have a name for this puzzle. I'd nominate "Mastermorphix" since it seems to be somewhere between a Master Pyraminx and a Pyramorphix in how you play with it.

I'm not 100% sure how old this Pyraminx is. The owner of the Arabesk puzzle shop in the Netherlands sold it to me cheap because it was broken. It was black plastic with rounded corners. I'm pretty sure it was a new Meffert's Pyraminx. The center is a white nylon ball. By the way, the Arabesk website is at:

http://www.arabesk.nl/

They have really nice puzzles and art objects.

I like that. Mastermorphix.

Joshua, had you seen the puzzle before? Like at the 3D Construction site? Or did this come to you in a dream?

I like the name.
Now tell me how to build one
I kinda know how to build it... but how do i cut the corner - 3 edge segment on that angle?
its kinda hard to cut that way... I have tried making a 4x4 cuboctohedron, and its really hard to cut that way.

I score diagonally across each face to provide a guide. The hobby saw usually follows the path of least resistance so it'll stay in the grooves.

That's the theory, at least. It works great on a mini-cube but I don't have any advice for a full size cube.

Yeah, that's what I suspected... but Morphinx sounds like a possible name for a Meffert puzzle.

The Mind Bender, UFO, and Tricky Disky all appear to be slight design variations on the same idea, yes. I don't have any of them yet, but the Mind Bender and Tricky Disky are both en-route. The UFO (I'm assuming you mean the one on Meffert's site, not Rubik's) looks really lame to me, so I haven't bought one yet. Is it as bad as it looks!?

Sandy

I was sent a photo recently of the 3x3x3 terahedron. Photos coming soon. (I am so behind).

Anyway, I also have the pieces modelled in blender.

>> Joshua, had you seen the puzzle before?

Nope - only the theoretical description at Jaap's site. I took 4 corners off a cube and stared at it a bunch. I had no idea what the completed puzzle would look like until I played around in PhotoShop for a while.

>> Like at the 3D Construction site?

Perhaps subliminally - I've visited that site but didn't remember seeing that tiny picture until it was pointed out.

>> Or did this come to you in a dream?

Hah, I wish.

Ill give it a go maybe in a week or two.
Right now, im in the middle of building a model house for my architechture class.

I ordered 5 original 3x3 mini (solid cubies) for $18.00
as soon as i get them, i plan on doing a 2x3x3. If that works out ok, i'd like to give the Mastermorphix a go. Looks like a great puzzle.
Ill have to think about how to restrict 1/4 turns.

Sandy, read my review on this puzzle:

http://www.zeta.org.au/~sausage/twistymegasite/ufo-review.html

I hope it helps you decide if it is worth it or not.

Doug.

I have a cheap knock off version, (maybe that's why my octaminx is falling apart) and it is solid plastic. I have several different brands some of which I have cut into for several reasons and I have yet to come across a hollow pyraminx piece

[url=message3267.htm]http://www.network54.com/Hide/Forum/message?forumid=43402&messageid=1018276937[/url]

Also try using a file for cuts like these. I have a whole selection of them that I've been using, and I find them better than the saw. They take more work, but the end result has a greater degree of precision.

Better yet, maybe a combination of both will work best. Cut close, but not so close that you're into possible error territory, then use the file to remove the last half centimeter.

Just a thought.

Sandy