Dave d, thanks. I have something similar filed away which only goes to 30. I used the formula/calculator today and managed to make a radius stick, by screwing a strip of ply to a strip of mdf at their centers, 24inches long. I then wedged each end with shims of wood and checked the sag until I was satisfied, then glued the wedges in place. It all looked arc like along the ply strip, quite uniform with no obvious flat spots. So i regard it as job done successfully.dave d wrote:Mike, I've used a diagram of various radii to make a few wooden templates. A fellow on the ANZLF forum made this. You can print it out at 100% on a few 11x17 pages, carefully taped together, and then cut them out, trace onto wood, etc. It's a good exercise to use the formula Dave provided, and then measure the arch. Hopefully they match!
I think I have a different version at home with a 40' radius. I'll check later.
thanks to everyone , Mike.