On Thursday, October 12, 2017 at 5:59:44 PM UTC-4, -MIKE- wrote:
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?


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
www.mikedrums.com

Protect the door and rip out the wood back to clean bricks. Rip some Luan or door skin into 2'x8', however many it takes to span the opening at ground level. Tack it together and tack it to the frame so it stands verticaly. Drop a plumb bob from the bricks to the luan and make a mark. Touch each brick or every few inches, whatever works for you, and make a mark. Work side to side plotting as you go. Connect the dots and cut on the line to describe a rough copy of the arch. Hold it up and scribe it close for a good fit. Transfer the arc to the new material. Works every time.