Date: Thu, 06 Jun 96 11:54:46 +0100
~~~ From: Andy Southern <a.southern@ic.ac.uk >
~~~ ~~~ Subject: Re: Fragile parts in 4^3, and limits to a n^3

At 08:35 04/06/96 -0400, you wrote:
>On 1 Jun 1996, Wei-Hwa Huang wrote:
>
>{Mostly snipped}
>
>> As another aside, I don't understand the rationale behind the canonical
>> 4x4x4 design. It would seem to me that it's better to have two rings of
>> grooves in each dimension, so that the face pieces could have "fatter"
>> legs and not break off as easily.
>>
>> Wei-Hwa Huang, whuang@cco.caltech.edu, http://www.ugcs.caltech.edu/~whuang/
>
> It probably isn't necessary for the legs to be so thin; the mechanical
>engineer probably had optimistic estimates of the likely forces and the
>strength of the particular polymer used. The latter isn't, by any means,
>cheap stuff.

It is compared to those injection Moulds that they had made. These will be
the most expensive parts for each puzzle. The more variety of parts, the
more expensive the puzzle.

I reckon that on a 3^3 there must be at least 6 different classes of parts
(the centre pieces on each face have a main part and a cover). I reckon that
the Megaminx has 5 as well. I have not taken apart a 5^3 yet, but there must
be about 8 or 9 if it works on similar lines to the 3^3. This almost doubles
the overheads of the 5^3 production compared to 3^3 production.

This Brings me to two questions (well three really, but the third is
unrelated) :

1) Who has the Injection Moulds for the 4x4x4, and are they still in
functioning order?
2) How many 7^3 (okay, I know there is currently no design) could possibly
be sold, and do you think that this would cover the costs of injection
moulds (optimistically about 15 or so) and construction (even allowing for
the Retailer to take ~70% of the price)?

my third and final(?) question is:

3)With all this talk of Who is on our group, is there any reason why the
mailing list can't be published? And if not, are there any of the designers
of Rubik's Range or Similiar? Any Company Executives looking for new Ideas?

Tar, Now I've got to go, I've got an exam to fail..................

Andy.