How should I attempt a flat curve

[Marc]

I cut an L shaped wall in half in my house. I had to leave a couple of load bearing beams in place. Now it is open from one room to the next and I would like to cap the half wall section with wood as a "shelf".
There are 3 sections....one end is about 45" long, the other end is about 27" long.......and the middle piece is actually a curved section.
I plan on using walnut about 6 1/2 inches wide for a little overhang on each side of the wall. Since I'm a bad carpenter I plan on making oaktag templates of all the sections. When I get to the curved part, assuming I have a template, how should I lay out the walnut to trace the pattern on?
I'm thinking,,,make a 90* (like a picture frame corner) and cut the curve out of that. Then, wouldnt I need a much wider walnut board to start with? Right now my board is a bit over 7 1/2 inches wide.
I may have asked this question 10 years ago here but I never did it and forgot any recommendations. My wife finally ripped into me about it. Lol

[ez-duzit]

Use segments to make up the curve, as depicted in this table.

[daddo]

What's the radius of the curve?

[Willyou]

It is difficult to make a recommendation without more details; mainly, what is the radius of the curve. A drawing would help. Having said that, if I understand what you are trying to do correctly, I think that your "shelf" would look best if it were cut and joined in such a way that it had straight segments with each segment having the grain tangential to the radius. Because your board is only 7 1/2" to begin with, this might be difficult without edge joining to make wider segments. I suggest you make "boards" out of cardboard and lay them out on the curve to see what it takes to achieve the best look.

It looks like Ez-dusit, daddo, and I were typing at the same time. I agree.

[Marc]

I'm atrocious with math but I followed the directions from online to get the radius. It was 25" from edge to edge and about 4.75" deep. I got 18.822
I have no clue what to do with that number. Plus the curve itself isnt perfect. Here a pic

[ez-duzit]

It would be a simple affair to laminate the curved piece from 1/8" strips, over a form, rather than assemble it from segments.

[Willyou]

No math required. Get a large piece of cardboard that will cover the whole curve. Lay it onto the top of the wall and trace the inside and outside edges onto the bottom of the cardboard. Now you can lay that on the floor and lay your boards on it to see where cuts are needed to make a series of segments to go around the curve. Like this . Since your boards are only about an inch wider than the wall, I would consider making them wider by edge gluing two pieces together for each segment. You will be able to make the curve with fewer segments that way.

Another way you can do this is to get a sheet of 3/4" walnut veneer plywood to make your curve. You will then need to edge  band it when completed. Or, use walnut looking plastic laminate over plywood or MDF.

[Marc]

Thanks Willyou. I was thinking along those lines but wasnt sure. I was also looking I to walnut plywood, cutting my boards to make the edges, or buy edging, but I wanted to router the edges. I'll do the cardboard idea first.

[Willyou]

I wonder what it would cost to have it cut from granite or man-made stone? It would sure look good.

[museumguy]

ok, I just had a thought. How are you going to treat the joint on the underside between the wall and the bottom of your shelf ? I usually see some type of molding used, this may mean a wider shelf is needed.