When at first you don't succeed

Make it out of Metal.

 We're keeping the door

 Ordered some 120 degree pipe connectors from Creative Shelters in 3/4" conduit size

 each wall section is 6', the Conduit comes in 10' lengths

 Center ring made out of leftover conduit bent to 60 degrees

roof poles before finishing making the ring.

so in a few weeks time we accomplished what we could not in wood. Our Desert environment just wouldn't let us do it in wood. lesson learned.