Trim for half round window

[Mike Elo]

I need something that will bend to trim the inside of a half round window. Approx. 3/4" thick, 4 1/2" wide. Looked a flextrim but not impressed. Don't realy want to steam anything for just one window. But I could. It's a 30" wide window. Thought of scarf cutting some MDF then bending but am afraid it will break easily. Can MDF be steam bent? It will be painted. Thanks.

[Fred LeBail]

I would use 3/4" plywood for this project. Make saw kerfs on the back side of the ply about 1/2 " deep. Space them so the ply will bend ( you will have to try this on scrap).You will be surprised how much it will flex.
I have gotten good results on tighter Radi than you require using this method.


Good luck !

[Per Swenson]

Depending upon which kind of finish you plan on using,Paint
or stain, resaw stain grade lumber to about 3/16 and glue it
up. If you are going to paint , 6 strips of 1/8 inch hardboard
laminated will work just fine. just remember to fill your reveal
before you case it.
hope this helps
Per

[Jim Becker]

Or...you could find someone with a William & Hussey Molder and have a round molding made to suit or even do it in your shop with template routing with multiple cutters and so forth.

[Alan Turner]

We installed a 4 foot arch with arch topped french doors to the master bedroom. To handle the details, I used bendable ply for the jamb, two plies, glue between, and shot them in. When the glue dried it was quite stiff and strong. for the casing, I laid up two thickness of 3/8" pine, scarfed with the joints offset, and used the BS to cut the arc, both ID and OD. I thne used a router to amke the first step cut, filed a scraper, and scraped the profile to match the rest of the casing on the door, and in the house generally. Not too bad a job. Got a quote for the two arches at $500@. That was when I decided that I surely could handle it.

[Robert Ducharme]

Very similar to what Alan said,

Cut out templates of the inside of the window so you have a form with a back that is the radius of the window and a other side that is the radius of the window minus the width of the trim.

Cut your wood to 3/32 - 1/8 thick on band saw (see what bends at that radius without breaking. Make enough veneers so you can create the trim to the correct thickness. Then using plastic resin glue, glue these up and clamp them between the forms (clamp forms squeezing the sides together until the bend is complete.

Let cure and remove glue on edges ... attach to window after cutting ends off where you want them.

This is very similar to what David Marks did to create a curved lamp stand.