Blanks for Curved Mouldings

Two ways to make curved blanks for machining into radiused moulding. May 5, 2007

Question
I am making curved trim. I have made my blanks from MDF and solid wood. How do most of you glue the ends of stock together to make curved moulding? I have used scarf joints with a lot of success. I have also glued strips together. Both are very time consuming. I know some finger joint the ends. How do most people make blanks for curved moulding?

Forum Responses
(Architectural Woodworking Forum)
From contributor B:
An old timer that I used for my radius work for years always gave me segments which were fitted on the job, butt joint with biscuits. Paint grade was poplar; stain grade was out of the same wide board, if possible. I would prefer that the stock be pre-glued and then moulded since the joint is perfect, but he would not do this. Others I have used since, cut out MDF blanks in one piece on a CNC machine. Solid wood is glued up as wide boards (or precut to rough shape) with butt joints and biscuits, then the radius is cut with the CNC or band saw. The placement of the biscuit is critical. I am not a fan of FJ since it is visible down the road and unacceptable for stain grade. Laminations are too time consuming and not acceptable for stain grade to me. The joints have to be made somewhere. It's just a matter of who gets paid for them. I think it is a better job when done in the shop.


From contributor L:
We make a lot of curved casing. We give a choice of laminated strips or finger joined. The strips are made on a straight line rip saw and come off the saw clean enough to glue. Each board is V-marked on the face prior to ripping, so if the strips get mixed, they can be put back in order. We have a slotted holder on a cart so the strips are kept in order. Glue up is done using 3/4" steel banding on an adjustable steel jig frame. Very good tight glue lines result in a molding that most can't tell from solid. Finger joined arches are made from one wide board, miter cut, run with a miter carrier on a shaper for the fingers, then the rough curved shape is cut on the bandsaw, leaving clamping ears. By keeping the parts in order and paying some attention to figure, it looks much like a solid board. Final sizing of the blank can be done with the band saw and edge sander or on the CNC router. We use the same molder knives for the straight moldings as the arch shaper so the match is very good. Most installers use a decorative corner block between the curved molding and the straight. If the pattern will hold a Lamello, I like to do that.

Photo is of our arch molding shaper.