How to cut an arch?

[dennis thompson]

I am trying to build a Welsh cabinet. Across the front of it,in the middle just below the drawers ,is a decorative piece which has three small arches cut into it, equally spaced across it. Each arch is about 12" long, with the arch in the first & last three inches and the center section of about 6" flat. I have tried to make a template for the arch & have cut out some test pieces & every time the arch on the left looks a little different from the arch on the right, i.e. one arch is rounder than the other, flatter than the other, etc.. (The template is just of one end of the arch, which I use to draw both ends of the arch). Any thoughts on how to do this ? I need to wind up with one piece of wood with three identical arches in it so you can see I have lots of room for error (& I've already wasted a lot of wood in my failed experiments)
Thanks
Dennis

[Bill White]

I usually draw a profile of half of the arch, then flip it over so as to have a duplicate.
Bill

[Rod Sheridan]

Hi Dennis, if you are drawing one half of the arch, and flipping it, it has to be symetrical.

The next step is to make a template out of plywood or MDF to act as a guide for a router or shaper bearing. Make the arch in the template for the middle arch location, then you can move your work piece along and machine the other two identical arches.

If you make the template accurately, the curve will be fine, and it will be perfectly duplicated it in the three locations.

Regards, Rod.

[harry strasil]

take a piece of old bandsaw blade, a yardstick or just a thin strip of wood and bow it to the arch you want, then tie a string across the ends to hold it there and lay it on your workpiece and draw around it.

http://img.photobucket.com/albums/v81/irnsrgn/layout/bsawblades003.jpg