SubscribeDave has been talking about wanting to build a pyramid, similar to our dome, for dance events, etc. I think it’s a cool idea and so I started doing the math behind the structure.
The idea is to build a pyramid structure out of short segments of ABS pipe and join the ABS segments together with larger diameter segments of ABS that are bound to the plastic skin of the structure.
The flat parts of the structure are pretty simple: at the joints there is a horizontal joint and 2 diagonal ones that continue the triangle shape up the side of the structure. The places that the pyramid requires a little thought is the edges between the faces and the peak.
At the edge seams, there needs to be one joint that connects a line of ABS from the corner of the base to the peak. There is another joint that carries the horizontal line from one face onto the next. Finally, the 3rd joint connects one triangle from one face to another triangle on the other. This was the angle I needed. This is also the angle from the peak of the pyramid.
I was surprised to see that the angle in question is 90% (provided the triangle segments building the pyramid are equilateral).
Neat. Time to get building!
by stephaloo, on October 6 2004 @ 7:36 pm
man oh man Rick – you are SUCH a wiz! When I was learning all the sin/cosin/tangent crap in school I never thought I would need it.
You both amaze and frighten me lol.