Subject:
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Re: How to make a perfect octagon or hexagon?
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 10 Dec 2007 14:27:30 GMT
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Viewed:
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10894 times
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In lugnet.technic, Joe Strout wrote:
> I'm trying to make a largish... octagon or hexagon out of
> technic parts.
Try approaching it in steps. Can you make an equilateral triangle out of
Technic beams? Don't worry about making the angles rigid, just make a structure
with three equal-length sides, connected near the corners (connected with
something that allows that angle to vary). When you connect the three sides
together, they will form 60° internal angles, because the three sides are equal
(not because you have a magic piece that provides that 60° angle).
Now take six of those, and connect them edge to edge. You've got a hexagon.
An octagon wouldn't use equilateral triangles, but using the same technic you
could get close I suspect.
Here's an example of some equilateral constructs (although I'd not use the
double, slightly stressed connections he does), and in another section
(geometry) they show constructed hexagons:
http://www.brickengineer.com/pages/category/constructs/
> I believed that the bent technic beams... had a
> 135-degree angle, or at least some angle that would
> divide evenly into 360.
They do (sort of, some of them), but it might not be in the way you're using
them:
http://technic.lego.com/technicdesignschool/lesson.asp?x=x&id=1_c&page=3
The internal angles on a 3-4-5 right triangle are 30, 60, and of course 90
degrees.
A related question of which parts give you "easy" 120° changes in direction
has fewer answers. I only know of essentially three: Tribladed liftarms (as
Kevin mentioned, http://peeron.com/inv/parts/44374), tribladed plates
(http://peeron.com/inv/parts/32125, or better but rarer
http://peeron.com/inv/parts/2712), and the very rare but handy "Technic bush
with 3 axles" http://peeron.com/inv/parts/x1781 (yeah, from just one set it
looks like, and a pricy one at that).
The Technic angle connectors are in increments of 22.5 degrees, so they don't
hit the magic 60° marks either for a hexagon - but they should work for
constructing octagons.
--
Brian Davis
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Message has 2 Replies:
 | | Re: How to make a perfect octagon or hexagon?
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| (...) A 12-12-17 triangle is very nearly right, and has angles of about 44.9 degrees. I used four of them in making a stop sign: (URL) Note that all eight corners are nicely studded down. Joe and Brian wrote: (...) Well whaddaya know! I'd always (...) (17 years ago, 10-Dec-07, to lugnet.technic, lugnet.edu, FTX)
| | | Re: How to make a perfect octagon or hexagon?
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| (snip) and the very rare but handy "Technic bush with 3 axles" (URL) (yeah, from just one set it (...) That particular piece is showing up in more sets: The Batman Copter with Scarecrow's bi-plane has three of those pieces in the set, and the new (...) (17 years ago, 10-Dec-07, to lugnet.technic)
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Message is in Reply To:
| | How to make a perfect octagon or hexagon?
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| I'm trying to make a largish (20 cm across or so) octagon or hexagon out of technic parts. I thought this would be easy, because I believed that the bent technic beams (e.g. (URL) 32348>) had a 135-degree angle, or at least some angle that would (...) (17 years ago, 10-Dec-07, to lugnet.technic, FTX)
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