Date: Thu, 19 Feb 87 08:18:00 -0500 (EST)
From: Peter Beck <beck@clstr1.decnet >
~~~ ~~~ Subject: magic construction

RE: CONSTRUCTION

Since I have suggested that people might want to take their MAGICs apart I have
prepared the following directions. I would appreciate comments as to their
clarity and completeness.

...................................
For those of you who would like to take MAGIC apart and then put it back
together here are some hints. First get out your tools, a heavy duty paper clip
or a nut pick will do (black electrical tape is helpful for keeping the strings
in place when putting it back together) and then pull the string over the corner
of a square (strings do break, the weak point is the crimp so minimize the
pulling and stretching you do by the crimp also when you reassemble put the
crimp in the middle of a long channel). Keep doing this until the puzzle is
completely disassembled.

If you failed to take notes you may have missed the following. The loops of
string (they are actually nylon fishline and they are redundant, ie, each path
is taken by two strings, with 16 strings in all) are threaded through the
channels, one set of strings takes the long path on the front face and the other
set of strings takes the short path on the front face (the opposite is true on
the back face OR adjacent square) with both sets of strings going in the same
direction on the same face. Thus the strings on the front faces are
perpendicular to those on the back face of the same square. NOTE: The strings
are not really redundant. They are placed to maximize lateral stability (twist
of the squares). This is done by having the strings (there are two) of a given
channel routing form the same sandwiching order where they cross over to the
next square. The string that uses the long channel and the string that uses the
short channel cross at separarte points. Each string criss crosses itself at
this point (making 4 string segments at the cross over point) with one part of
itself in the NE channel and its other part in the NW channel. The stability is
gained by having the NE going string sandwiched between the NW going string (or
vice versa) for both crossover points, ie , sets of strings. Both patterns
shown below are used on the same set of three squares (THIS UNIT IS CALLED A
TRIPLET.).

```               string #1 in                    string #2 in
SHORT channel ON TOP       LONG channel ON TOP
for squares 1&3              for squares 1&3
---- ---- ----             ---- ----  ----
|/ \  |   / \|/ \   |            |   / \|/ \   |   / \|   TRIPLET
HAS BOTH
|\  \ | /   /|\   \ |   AND   | /   /|\  \  | /   /|   STRING
PATTERNS
| \  \|/   / |  \  \|            |/   / |  \  \|/   / |
|  \ /|\ /   |   \ /|            |\ /   |   \ /|\ /   |
---- ---- ----             ---- ----  ----
```

After having made two triplets there will be two squares free. They are used to
join the triplets. Place one of this extra squares between the two triplets,
ie, where the "AND" is in the diagram above and thread the strings through the
channels as if this square was the middle square of a triplet (REMEMBER THAT the
STRINGS GO ONLY ONE WAY ON each face OF A SQUARE). THEREFORE, THE ENDS OF THE
PREVIOUSLY MADE TRIPLETS WILL BE THE ENDS OF THIS NEW TRIPLET ALSO. THIS WILL
CAUSE THESE ENDS TO HAVE TWICE AS MANY STRINGS AS THE MIDDLE SQUARES OF THE
TRIPLETS AND IN FACT IF YOU LOOK AT MAGIC YOU WILL SEE THAT THE NUMBER OF
STRINGS IN THE CHANNELS ALTERNATES FROM SINGLE DENSITY TO DOUBLE DENSITY, ie,
either 2 or 4.

CUSTOMIZATION OF MAGIC

In the disassembly process an easy thing to do is to break the circularity of
the puzzle by removing one square, leaving a chain of seven squares. This can
be done by lifting the strings off a single density square. The square will
come out but its strings will stil be entangled with the puzzle. You will now
have to temporarily lift strings off the adjacent squares to disentangle them.
This can be done easily. You now have a chain of seven squares. Each hinge can
be manipulated without the constraint of being connected as a loop. A basic
hinge between two squares has the following motions:
NOTE: The flipping of the pieces changes the direction of the squares as shown
by the arrows.

```       POSITION  1                  folded  A            folded  B
________  _______          _________         _________
sq 1 TOP      sq 2 top           sq 1 on bot          sq 2 on bot
>>>>>>          >>>>>>             sq 2 on top          sq 1 on top
________  _______          _________         _________
```
```POSITION  2       >>>>>       A unfolded          B unfolded
________          _________
SQ 1 TOP             SQ 2 TOP
<<<<<<<<               <<<<<<<
________          _________
________          _________
SQ 2 TOP             SQ 1 TOP
>>>>>>>                >>>>>>>
________          _________
```

The robustness of this hinge permits the making of all possible planar patterns
that has each square butting up to the edge of another square.

```<beck@ardec-lcss>
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```