Like a circle in a spiral, a wheel in a wheel… and so it goes. Here’s another chance to practice the plumb cut on an arch. I start by assembling the inner arch with no glue, just tennons and pocket screws to hold it together.
Then I mounted the parts of the outside arch to mark the center and endlines and make sure everything is lined up.
After cutting the bottom (straight) piece to length I butt it up against the sawblade and clamp it to the sled.
I then placed the arch on the straight piece to line up the outside marks, but as you can see it is too long to rest against it on the end marks so trimmed I some of the excess with a jigsaw leaving a couple inches overhang.
I clamped the arch to the sled and to the straight piece and made the cut.
Then while leaving the straight piece clamped in place I rotated the arched piece and lined up the cut end with the end of the straight rail.
I re-clamped the arch to the sled and rail and made the other (parallel) cut. Then I mounted both pieces on the inner frame to check for accuracy. Works like a charm. Safe and accurate.
-- tim hill www.newcalshop.com