Yeap, turns out contact cement (not water based version, do work outside and don't smoke anything while gluing :)) and cordura work great for hinges. Although beefy brass zippers can be found on clearance when buying in bulk, I think more cordura flaps and some velcro to keep things from unfolding would be sufficient:
http://www.appropedia.org/BFD_mod Good luck and let me know if I can help in any way :) Vladimir On Thu, Mar 28, 2013 at 1:17 PM, Jacob Rodriguez <[email protected]>wrote: > So, I'm going to be building a quarter sized nearodesic polyhedron > ("quad") dome (1 rmax sheet = 8 triangles) for BRC this year. > > My foamcore and masking tape prototypes (1:12 and 1:5 scale) have been > going well. I'm learning how to do the tape hinges, and how to miter the > edges with a razor and angled metal guide. I'm thinking that the full size > version will be relatively easy to prepare and construct. My end result is > a 6' high, 12' diameter dome that folds down into a 4' x 4' x 15" high box. > Minimal tape is required as all but one edge of each quad is hinged with > fabric and adhesive. Only the top square, and 4 "corners" need to be fully > taped together. > > I'm seeing lots of people commenting on how the BFT (bi-filament tape) is > not really UV resistant, so it flakes off eventually. Also, that it's > barely a semi-permanent solution, even if you do tape hinges instead of > one-time assembly. I've considered many different types of ways to join the > triangles that would last more than one or two times: > > - zippers (needed like 400 of them, really really expensive) > - button snaps and straps (would glue on the snaps to the boards, then use > a strap to snap them together; this is not weather proof at all) > - velcro (again, pretty expensive if you use the really good velcro, which > is likely the only way to guarantee structural integrity and > 'weatherproof-ness') > - magnets (even using strong ones (N45), embedding them in the edges of > the triangles, they could jsut fall out, and still not weather proof. also > $$$) > > ..and a couple of other ideas. I've learned that putting metal > hooks/rods/bolts (binder clips) through the boards will just rip through it > with a strong enough tug. They could end up just getting loose and boring > out big holes. Using plus-shaped ("+") hooks/rods to fasten some sort of > fabric over the joints are slightly better because they resist being pulled > like a wire cutter through the board, but you would have holes in the board > and water could get in. Also, excessive force would also just make the > holes looser and ruin the boards eventually. But the idea of using some > sort of fabric seems to hold merit. > > My main goal is to build something that can easily be packed away, and > assembled multiple time. Realizing that the main principles of a good BM > structure are to seal out rain, dust and light, I think I've come up with a > possible solution, but I'm curious why I can't find anyone who has tried it. > * I'm hoping to get some cautionary tales or some encouragement on using > sport nylon (as opposed to ripstop), and some Super 77 or 80 or 90 spray > adhesive, instead of the traditional tape.* > > The cost might be a little more expensive up front (depending on some > factors), but I'm thinking that the nylon will last much longer than just > about any tape and is probably just as strong (if not stronger) than BFT. > From what I've read, a lot of people end up using some 77 spray anyway > because of the lubricating residue on the boards. I'm curious if it's more > UV resistant (or at least the adhesive would be) and therefore survive the > endless sun bathing better. Also, the concept of cutting fabric into strips > and using spray adhesive as a backing gives the user many more options when > it comes to materials (stronger fabric and/or stronger glue), rather than > just limiting to such a rare find as 6" BFT. Though I'm sure that sport > nylon "tape" is even more rare. You can also make the strips as wide as you > want, so you are not limited there either. > > I've built a prototype of a hinged triangle using foamcore, sport nylon > and Super 77, which seems very, very strong. Stronger than masking tape > anyway. I'm thinking that while it's not waterproof out of the box, I could > always spray with some scotchguard, or tape over everything with the foil > tape. Foil tape would also help any concerns on fire-hazard as the adhesive > is quite flammable. I put a hairdrier on it for about 10 mins on high, to > see if excessive heat made the glue loosen, but it did quite well. I'm > thinking the higher temp ratings of 80 or 90 adhesive will help in that > area. Maybe instead of foil tape. I can spray with some sort of coating > that will protect against fire and water at the same time. > > For cost comparison, my project would be using about 6 rolls of 60yd tape. > That's about $20 a roll. Plus about 4 rolls of foil tape (for outside only) > at another $20 a roll. I'm thinking that a can of adhesive will last quite > a long time, so I may only need about 3 cans at about $20 a pop. The fabric > is not that expensive (maybe 5 dollars a yard), so I think all in all, I > might come out saving a little cash (if any at all), but ending up with a > much more permanent/reusable solution. > > Anyway, what do you all think? I'm going to be purchasing a piece of > polyIso to test. I'm going to make a single "quad" using this nylon and > adhesive, then leaving it up on my roof for a week or two to see how it > handles the weather. It's Santa Monica CA weather so not quite the same, > but should give a good indication as to whether it will survive at all. > > Thanks for reading! > > > > > -- > You received this message because you are subscribed to the Google Groups > "hexayurt" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/hexayurt?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "hexayurt" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/hexayurt?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
