Grain standards for radius mouldings
Standards methods for joinery of radius mouldings, with exposure of end-grain in mind. June 6, 2001
What is the standard for grain direction and joint joinery for stain-grade radius moulding?
I am assuming you want to show little or no end-grain, but then you must use several pieces joined end-to-end, and I'm not certain of the best method to do this inconspicuously.
I have had good results in the past by simply butt jointing the segments of radius work. I generally try to use dowels, where it is possible. Sometimes you can use biscuits if you are positive they are not in the profile cut line. Take a little extra time to match your grain pattern and color at the joints if at all possible.
Another way is to rip the stock into strips thin enough to follow the radius, then glue and clamp to a form. A pencil line across the face of the board helps line the grain up again. You also want to keep the strips in the same order they came off the board. A two piece form is better than one for even pressure.
If I don't have time for that type, I've used biscuits and finger joints with good success. Too few joints will give an angled pattern to the grain and make you use a wider board.
Our method for stain-grade arched moldings is to divide the molding into equal radius sections as wide as your stock will allow, ie: typical window arch may have 4 sections covering 45 degrees each. We sometimes will edge-glue a couple of boards together if we don't have stock that is wide enough. On some higher-end work, we may even book-match the grain so it is balanced on both sides. But most important is to have all sections equally mitered around the curve.
We also segment the radius. What I like to do is lay out the radius on a sheet of plywood and position the sections to locate the joint area. I look at the position of the joints as though the perimeter is a clock--this way the segments join equally at both sides.
I believe book matching on stain grade is a must.
Has anyone done radiused crown molding? For paint grade, we rip up the crown on the band saw and bend, glue and pin it to a form, but what to do with the stain grade?
We make our curved crown by layering segments to build up a triangular block, which get passed through out tilt-moulder. Our casings are segmented (typically 16" long segments finger-jointed end to end), and the crown is, in effect, simply individual casings layered one on top of another.
There are, of course, a good number of other small details, but that is the basic scheme.