by jondbar628 » Mon Jul 31, 2017 9:20 pm
My build is similar to your "softened" rounded version. It's a 5 wide 10 ft. Sorta weekender, with a narrowed, rounded nose (kinda like yours). I wound up doing the rounding by hand after after abusing a lot of brain cells trying to devise a hot-wire jig to do the job without jig deformation, etc. Decided to spend the time by doing instead of pondering. worked out OK using a coarse file, followed by increasingly finer sandpaper, down to 180 grit. 80 grit was very effective and good to work with. Lotta dust masks....
I believe quite a few folks have done rounding on foam corners, if I remember correctly. The compound angles didn't really present much of a problem (at least as far as rounding went). I did not add additional support such as a cornice, although I thought about doing so. The double thickness of canvas due to overlap inside & out left the roof-to-wall joints rock solid.
The cuts for the angles (other than the roof) leave you with a thicker cross-section than the original 2" foam, so you can shave & round them without losing much, if any of the original thickness. plus the angle adds strength at that joint............I can't say if the canvassing was more difficult due to the rounding, since it's my first build, but the compound angles can be challenging when using PMF. At the front upper in/down angle, I wound up with three layers of exterior canvas in a small area on both sides......On the bright side, it's really, really strong there!..............jd