Date: Fri, 13 Dec 91 14:50:03 -0500 (EST)
From: Dan Hoey <hoey@aic.nrl.navy.mil >
~~~ Subject: Big groovy cubes, revisited

Tee Luns writes:

... one of the last posts in cube-mail-7 triggered something in me
head. The suggestion was to use a fresnel saw to cut all the
cubelets out of a single chunk of material....

Well, I'm glad that my silly ideas triggered something. Sometimes I
wonder if they are as amusing to read as they were to write.

... why not a simple dovetail?

Certainly a dovetail would do it. I guess when I got to sharpening
the fresnel saw I didn't know when to quit.

... have the dovetail/cubelet pair separate, ... screw the dovetails
(which are already in their grooves) onto the last couple of
cubelets.

Surprisingly enough, this is just how Rubik's Revenge is put together.
One of the center cubelets (perhaps always on the blue side) has a
screw that joins the outside of the cubelet to its dovetail. You can
usually find locate it by the dimple in the colored sticker.

If the dovetails go right to the surface, one has to be *VERY*
careful.... The solution is to make the dovetail taper off at its
ends.... This will lead to holes at the surface though, so the cube
won't be too pretty.

In the 7^3 and larger, they have to go through the surface, and even
if they were squared-off dovetails they wouldn't match the color of
the adjacent square except in the solved position. Unless of
course we make the outer layers thicker, as Dale Newfield mentioned
when we were discussing this back in May.

A novelty with this approach though is that no centre is
required. We could build a hollow 3x3x3 cube with face centres
hollow, and see right through the cube....

But, if we had the smaller odd-sized cubes trapped inside, not
only would they help hold the outer layers together, if we made the
cubelets mostly transparent, we'd be able to see what we've had to
imagine in the past. Now that'd be one heck of a puzzle.

Wow, I want one! But I don't think the material really needs to be
transparent, as long as the face center pieces are hollow. It would
help let light in, though.

Dan Hoey
Hoey@AIC.NRL.Navy.Mil