I don't yet have pics, but I do have progress, and some stats so you all can get an idea of the project size.
The dome uses 6.5 sheets of polyIso board. It will be cut into 48 acute triangles (8 per sheet, 4x2x4.47), plus 4 right-angle triangles (4 per sheet) and a large 4x4 square. To tape every edge, I'd need about 600' of tape. 600/3=200yd/60yd = 3.3 rolls of tape (or equivalent) I'm not sure if I'll be taping every edge, or just using my replacement material to cover the edges as I make tape hinges between all the pieces. If I use material, I have 112 joints/edges to cover. 96 of those edges need to be hinged (24 edges per quad, 4 quads (duh)). The other edges are the right-angle triangles, and the top square. Since the rolls of material that I've been testing are wider than 4.5 feet, I only need to multiply 112 by the width of my strips to get the length of the material that I'll have to use. 6" strips * 112 joins|edges = 672" of material = 56ft = 18.6 yds of material at 4.5' wide. Not too bad as long as the material isn't too expensive. I've found some 4 gauge clear vinyl that is working extremely well. It's cheap at $2.99 for a 4.5x1yd piece (2.99/yd), so even at 19yds, It'll be about the price of single expensive roll of 6"BFT. It's also much thicker, and made to widthstand hot/cold outdoor type environments. I cut the vinyl into 3" strips. (My test board is .75" so I may need to go to 4" strips during production, so that's 4*112 instead of 6). I've been using contact cement to glue it to the boards. The glue I bought for testing purposes was about $4 for 3oz. and you use about .75-1oz per join. I have 112 of them, so.. yikes. I'm sure I could find it cheaper in bulk and a way to use less. Spray adhesive is probably just as strong, but it's messier, you waste a lot, and it's more expensive. Contact Cement is super duper strong, I'd say stronger than the foil facing is bonded to the paper facing. Probably about as strong as the paper facing is bonded to the foam itself, if not more. Sorry, I don't have pics yet, but when I get the chance, I'll put some up. To miter the edges, I found an iron guide that's 3' long, and does a nice 60deg angle. It's an "L" shape that's about 1" on one side, and about .5" on the other, just like a capital "L". When you lay it so that the board is the hypotenuse, the short limb is a nice 60deg angle, that I just run a razor blade on. I found that the trick is to not try a single pass cut, but rather to take several passes, doing a little deeper each time. It comes out much smoother and it's easier to keep the razor pressed against the guide. It's one of those trapezoid razor blades, and I just use bare fingers. Seems like the best way, and the less the pressure the better the result. I now have an easy, cheap way to accurately miter the edges and make a more accurate build. The vinyl should be pretty durable, even in the sun, and since it and the glue is waterproof, it will work really well in the rain. I've tried to pull two triangles apart that only had the vinyl applied to one side, and it was even the hinge side, so some of the vinyl is glued directly to the foam (which should make it less secure). It did not. I was unable to pull the boards apart with a good deal of my strength. Pics soon I promise. I just wanted to tell you all about my progress thus far, in case it sparks any other ideas/projects. Thanks! -- 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.
