This is very cool! Let us know how vinyl is holding up in the sun - I am sure it should be fine for a couple of weeks.
A couple of related shortcuts I found are: 1. Walmart sells contact cement by the quart :) 2. To cut foam, particularly thick 2" variety, my Fine Homebuilding magazine suggested taking a putty knife (I used 4" blade) and sharpening curved outside edge. This goes through polyiso like through butter, but making several passes is still a good idea to avoid tearing the foil. 3. For the edge guide I just ripped a 2x4 at 60 degrees - it gives over 2" of surface for the putty knife to slide on. You do want kiln dried 2x4 to avoid warping. Can't wait to see the pics :) Vladimir aka chaynik On Tue, May 7, 2013 at 11:50 PM, Jacob Rodriguez <[email protected]>wrote: > 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. > > > -- 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.
