Started on the seat backs - 5.5 hours

 Feeling like fabricating and not riveting today😛. I decided to tackle something new. I dug out angles and hinges and cut all of the parts for the seat backs. 

  A groove is required to be cut into the seat back angles to allow the hinge to nest. I've seen lots on the build log use files to do this, but I found that a router works extremely well on aluminum (yes, dulling the bits to no end but its worth it). 

Still have the router out, using a round over bit I put a radius in the angle that crosses the top of the seat back.