You are correct. 72 degree angles for the pentagon pieces (72 x 5 = 360) and 60 degree angles for the hexagon pieces (60 x 6 = 360). Remember though, the pentagon struts are involved in a hexagon on the other end so they will have a 72 on one end and a 60 on the other. Don't forget to mark them. Also, to cut a 72 degree angle you need to cut 54 degrees off each half of the pentagon side since 180 - 54 - 54 = 72.

One more question for you: Did you simply use 72 and 60 degree angles for the arrow head cuts? It seems to me that there would be be some variation around these angles depends on the piece, but maybe I am thinking about it wrong. Or maybe it is just close enough and works anyways?

Fastening the cover took a while for sure. I cut hourglass (6 triangle), pentagon (5 triangle) and pyramid (4 triangle) shapes from the poly and stretched them taut onto the dome using wood clamps and ratchet tie downs. This worked well but was a real pain. The company that sells the woven poly supplies a 1" plastic lath (~1 mm thick) that is nailed onto the 2x4s on top of the poly. Each strut in the dome is covered with the lath. Bit of a project but hopefully won't have to be replaced for a few years at least!

We are in the U.S. in Tennessee

Cool Dome. I built one last summer in NB in the east coast. were abouts are you guys.

Cool. I'll look into it. How did you fasten your cover to your dome?

Yes, helpful, thanks. When your plastic wears out, if you don't want to do the serious upgrade to the keder or polycarbonate, I would suggest woven poly from Northern Greenhouses (may be other suppliers too). It is the same plastic as in normal greenhouse plastic, but is woven like tarp material, making it more translucent and super strong. I used it for my first dome and it is great, no problems and has a foot and a half of snow on it at the moment, very tough stuff. Have fun in there!

Price was an issue. Since this is our first attempt we didn't want to put a lot of money into the cover since we might have ruined it and we thought we'd see how greenhouse film preforms before investing in the poly. It actually would have been the most expensive part of the dome. We actually had a hard time deciding what to use as a cover (poly keder, greenhouse plastic or polycarbonate ) and chose to go most economical first as a test. We are in the south and don't have much of a winter here so heating the dome isn't much of an issue. The temp. is in the 30's today and it's nice and warm in the dome. And that's without any water to serve as thermo mass so the greenhouse film seems to be sufficient. We'll see how things grow later.
As far a labor, we worked around 30 hours over a 8 day period. That was mostly just two people. We needed three levels of scaffolding (15 feet high) to reach the top. Hope that helps.

Cool thanks! I also noticed that you decided not to go with the poly keder cover, was this price motivated, or just more complicated to install? How long did it take to erect the 40' once you had the pieces cut?

Well, the 40' was huge. We found we didn't need to go so big. The ground space was nice but the height was crazy. The 24' suits us better. As for what went wrong, I think our ground wasn't completely level although we built the 24' on the same location and it came together perfectly. The 24' is a 3v and the 40 was a 4v. When we got to the top we were having to pull in on one side and push out on the other and all this stressed the base pieces and some started to separate. We were 8 boards away and we probably could have finished it. We also had a problem with some warped boards. I really like the arrowhead connections. Both domes were very solid. The manual had us scratching our heads sometimes but we were able to figure out what he was getting at and overall we were satisfied with it. Good luck and thanks for watching.