"-MIKE-" wrote in message news
https://photos.app.goo.gl/DqXrs5DI2roJTli22

I need to replace the white board above this garage door. The 2x12 is
rotted out pretty bad. It will just fall out when poked with a screwdriver
or putty knife, so I'm going to replace with a new, treated 2x12. (Client
wants cheapest option.)

What I need help with is figuring out how to transfer that arch to the new
2x12. This isn't an arch that was drawn with a radius or trammels. If this
was a perfectly cut arch, I could just determine the radius by bisecting
the chords and extending perpendicular lines to find the radius.

If you look closely, you will see that it's not even and the arch "flattens
out" near both ends. So I believe I'm left with trying to transfer the
exact line of the bottom of the soldier course of bricks to the new 2x12.

Remember, the existing 2x12 will not come out in one piece or even several
pieces which could be reassembled to use to trace the "arch" onto the new
board. It's pretty much, mulch, held together with paint.

Any ideas?


It appears as though the 'mason' used a springy board to scribe/cut the
field bricks, then again to support the arch bricks. This shortcut explains
the straight ends. The tightest curvature at the apex is the result of the
flexibility of the springy board and the amount of pressure applied from
below.

I think the best way to match the arch will be to scribe vertically with a
large compass as suggested by other contributors.
Scott in Dunedin