Trimming Out Arched Windows

Question for all of you trim carpenters out there, because I am definitely a novice at doing trim work.

My question involves trimming out arched windows. The millwork supplier(who also supplied the windows so he know the arch diameter) sent out 3 pieces of 2-1/4" wide casing trim for each window that amounted to a little more than half a circle. The problem that I am having is that the pieces are soo irregular you cannot get a decent fit for the correct radius out of the material that is supplied. If I stack the 3 pieces on top of each other they do not all follow the same curvature, which I would think they should. Is this typical for arched window trim, or should I tell the millwork supplier to take the crap back and get me something I can work with. If I only had one window to do, it wouldn't be such a big deal, but I have seven to do with 3 different size diameters. I even tried using pieces for other windows with the same diameter and couldn't come up with a combination that was acceptable.

 

Start at the middle top, decide your reveal and proceed proportionally down both sides, after trimming both ends of the center piece, cutting the successive down legs to fit.

 

I am going to imply by your response that the material that was supplied is generally the quality of material that is supplied by millwork suppliers. I tried doing what you said by drawing out a half circle on the floor and trying to lay the pieces out to that circle, but I can't find a combination that works.

 

I would send it back for some that fits.

 

If you've layed it out on the floor and using #6 finish nails as pegs, placed at 1/2" intervals and attempted to form it to conform using the pegs at about 8" at the outside of the formed moulding and you are still umable to make it work, then take it back.

 

I got them to work somewhat. The one's with an 18" and 24" radius do not have a smooth transition from one piece to another. My helper referred to it 2 arcs and a bump since there was always one piece that wouldn't match up exact with the adjoining piece. The 32" radius pieces fit so well I couldn't believe it.

 

Sometimes the radius is not perfect and you have to fight it to fit. I had one that I thought would never work but by doing what one of the responders suggested, starting at the top middle and working down, I was able to get it to fit. If I'm understanding you, the actual profiles of the various pieces is different. If that is the case, then definitely send them back.