Geomag bar lengths and ratios

Geomag bar lengths and ratios

Postby karlhorton » Thu Nov 05, 2009 4:00 pm

The classic Geomag bars are approximately 27mm long and the new ones are 58mm,
the balls remain 12.7mm diameter.

Rounding slightly: that's 1" for old bars, 2-1/4" for new bars, and 1/2" balls.

For polyhedron building, what matters is the "distance between centers" which is,
therefore, 1-1/2" for classic and 2-3/4" for kids.

The ratio between these two is 11:6 (1.83) which isn't close to any
useful ratio I can think of.

Two ratios that would have obvious uses are: the cube diagonal (1.73) and the
golden ratio (1.61).

I happen to have a few 3/4" balls and see that for this size of ball the ratio is 1.71.

Here's a pentagram with 3/4" balls:
2009-11-05-pentagram.jpg
Pentagram with kids bars and 3/4" balls


See that the edges aren't quite straight. Also, at the sharp points the balls don't quite seat correctly because the rods interfere with each other.
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Re: Geomag bar lengths and ratios

Postby Wim » Mon Nov 09, 2009 4:29 pm

It still looks nice. And yes, I had considered the size of the ends of the Geomag bars making tight angles difficult.

I've been considering getting some Geomag kids (and then the panels version just for the silver bars) since I could not find much information about them. I'm a bit disappointed there aren't Kids Pentagons out there. Granted, my daughter has only used the squares and diamonds so far in regular Geomag, but it would be nice to have them.

I've held off on my purchase so far for two reasons: 1) My 5-year old loves the regular Geomag and given the amount of it at our house, she'd feel cheated if I gave her 'only' a box of 110 pieces or so. 2) There doesn't seem to be much synergy between Kids and Pro.
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