Arched Jambs for Circle-Top Doors

Quick tips on fabricating arched door jambs. May 16, 2008

I am making a couple of full circle top cherry doors that are to be pre-hung. I am trying to figure out the best way to build the jambs for these doors. I don't own any steam bending tools - only traditional tools. Is there a way to build these without having to buy anything out of the norm?

Forum Responses
(Solid Wood Machining Forum)
From contributor G:
Laminate the head round the desired radius form (ignoring springback), then make the trim to the same radius as the form, less (or plus) the reveal. Then when you install the jamb, make it to the correct radius by shimming, then the trim should fit with the correct reveal. The door can be made to the true radius of the form less the clearance. Note: trying to allow for springback only makes for more work.

From contributor W:
When we make this type of opening we try to have the door opening framed square at the jobsite taller than the door opening. We then provide the framing that makes the opening round. We attach our jamb to our radiused framing. Then install the jamb and framing prior to wall finishes.

From contributor O:
The way I do them (I'm a moulder operator by trade but I do this too) is to resaw my lumber down to 1/4" and run it through a wide belt (both sides) down to 3/16". I have metal L brackets that I screw into a piece of MDF with my arch laid out. Then it's simple lamination until you get your thickness (with a stop, it's 1.25" - I run it through my M&M moulder to cut the plows). Then it's a matter of clamping the laminated stock down to the L brackets and letting it sit. A little trimming on the tablesaw (careful...), make the plow, do a little angle work to connect the legs, and you've got yourself an arched jam.