SpaceFrame

Straws Straws make a simple, and extremely inexpensive modelling material for prototyping space frames. Straws have limited strength against lateral forces - but in hub-and-strut systems, the idea is that such lateral forces are avoided as much as possible - so this isn't a big deal. They are likely to have a limited lifespan - but they are so cheap that this hardly seems to matter much. Another good thing about straws is that they are very light. Weight can easily become very significant when building large models. What follows are photographs of a few straw models: Trusses Octet truss Dome on concrete (side view) Dome on concrete (top view) Dome on grass (top view) Dome on grass (bottom view) Dome on grass (side view) Hubs These are cheap plastic hubs. One of their faces is completely flat. Straws were also supplied - though using one hub resulted in the straws fitting the hubs extremely poorly - resulting in very poor tensile strength properties - which severely restricted the models which could be constructed. The supplier suggests using the hubs two-at-a-time "back to back". Doing this produces a much better fit with the supplied straws and results in a stronger joint - but it doubles the number of hubs needed to build anything with - and increases the resulting weight. My guess is that the reason the manufacuter doesn't join the hubs together themselves is because making them this way allows them to use a simple "half cast" manufacturing process - avoiding the need for injection moulding. I suppose it makes the hubs seem cheaper as well, if they count half a hub as a hub - though doubling the hub price would still leave things pretty cheap. I obtained these hubs from [here]. The hubs come supplied with lots of flash - which needs to be removed before use. Unfortunately, the hubs have no "stop" on the spigots - so the joins between the straws and the hubs tend to be rather imprecise. Since I only had a few hubs I didn't want to double them up. So I soon switched to using regular "neon" straws from my local supermarket - which I found fitted the hubs tightly enough to build reasonable models with - though the hubs pushed the straws into an unfortunate shape; reducing their resistance to lateral forces in the process. I joined the hubs together using brass paper fasteners - the same ones that I used for constructing this model - and [this model]. This was quick, easy and worked well - though I am aware that brass paper fasteners probably would not work very well in the intended educational context. Twin hub close up (from above) Twin hub close up (from below) Hub close up (from below) Hub close up (from above) Hubs doubled up (from above) Hubs doubled up (from below) Standard neon straws Misc No 5-way or 4-way hubs were available from my supplier. Fortunately, you can often do this sort of thing: Icosahedron Octahedron More octet truss fabric Dome on grass (close up) Dome on grass (close up) Links MUTR's straw system Astro-Logix TekKit Construct-O-Straws (Cochranes) Construct-O-Straws (Parker) Construct-O-Straws (Galt) Connecta Straws (Galt) Construction Rods Straws and Connectors (Roylco) Grafix Building Straws Molecular Model Parts Zome