Started Fathers' Day with some pancakes made by my elder daugher followed by hand-made cards and hand-made ceramic gifts from both daughters. Went to church, got some new Ray-Bans to replace my lost Oakleys, had lunch, did some building, had family dinner and swim at my buddy's then finished day with a little more building. What a great day!
Beveled the ends and rounded the edges of my bend-aid boards so they would not dent the mataterial as I was creating accurate bend angles. As a time and effort saver I started using my cordless drill to provide initial run-down of my brake bolts. Final tightening still done with ratchet.
Since the rear spar is a Z-bend the bend calculator is limited in it's ability to calculate an accurate developed length. I added the thickness of the material (1.016mm) and 1/2 of the bend radius (1.59mm) to the calculated double-bend DL figure of 112.79mm then rounded up to get a blank size of 116mm X 2200. Used sight lines just short of 18mm which yielded flanges of 20mm and 21mm with a web length - from tangent of 95 degree radius to outside of 85 degree bend - of precicely 80mm. Noting that the developed length specified on the drawing is 113mm I suspect this dimension would have worked out with perfect 19mm flanges.
