Hi Ron, James, Sofasurfer:
Are you making headers or arched ceilings or trellises?
This is part of a design theme throughout the house and outside. It is an attempt to unify all of the parts, the terrace in the back, break up the central wall with built-ins, and become a design element in the kitchen and bathrooms.
I think ellipses and ovals are pretty much the same thing, "a stretched out circle" although one is stretchier... er than the other. How accurate, (symmetric) the ellipse/arch is to be depends on the number of blocks and their positions are on the ply.
I figure the 14' ones will be "sort of" but once one is created, the others are easy duplicates. The interior ones will be 4'-6' and will be much easier to do but will be one-off each.
In the past I've made a couple 3 arched garage door overheads and breezeways.
In your case a sht of ply ripped in half along the 8' and 2X to hold them tight together.
Block the ends with 2X for the 14'W and a block in the center at the 6"H.
Pressurize a water hose from the house, thoroughly bleed all the air before closing off the end, (good water pressure helps) keep the house feed open.
Set the hose in the jig, butt it to the blocks and mark the perimeter.
Excellent mechanics. Well worth the examination and attempt.
The carport is 28' long with two "bays" between pillars supporting the roof. The front and back are 14'. These are "detail panels" that go below the beams and hide indirect lighting. Would you use a single circular arch, an ellipse or an oval?
Thanks for the help guys.