rudy de haas
08-02-2017, 6:59 PM
I am putting solid edging on 12mm (about 1/2") baltic birch. To do it I used the shaper to cut a 1/4" dado down the center of both 12mm: x 96" edges of the plywood (leaving about 1/8th on each side). To make the tongue part I bought 1 x 6": maple in 96" lengths, cut it down the middle to get two pieces each 1 x about 2 3/4ths x 96 and then cut these down the 1" side to produce two strips - one about 12mm thick, the other about half that. I then run the 2.75" wide (minimum width for the power feeder seems to be around 2") piece through the shaper four times to make two tongues and finally cut the strip twice to get the 96" x 12" x .6" strip that has the tongue part and f1/4" of solid edging.
Notice that this process starts with two long cuts at right angles to each other - and, later, a third cut that parallels the first one. What I've noticed in doing this is that the resulting strips all developed significant bowing - despite the act the boards started out pretty close to straight. The intermediate products (about 2.75" x 96" 12mm) bow as you would expect, but the strips when cut off tend to bow at right angles to that.
Does anyone know why? and,if you know why, can you tell me how to predict/minimize this? (In practice, they can be forced straight pretty easily during glueing - but why does it happen?)
Notice that this process starts with two long cuts at right angles to each other - and, later, a third cut that parallels the first one. What I've noticed in doing this is that the resulting strips all developed significant bowing - despite the act the boards started out pretty close to straight. The intermediate products (about 2.75" x 96" 12mm) bow as you would expect, but the strips when cut off tend to bow at right angles to that.
Does anyone know why? and,if you know why, can you tell me how to predict/minimize this? (In practice, they can be forced straight pretty easily during glueing - but why does it happen?)