Eleven Grooved Box Step by Step – Part 4: Plowing The Other Eight Grooves
Plowing The Other Eight Grooves
See the original “Woodwright’s Shop” video here.
I remove the lip strips and set them aside. Each gets pencil dots on the bottom so it can be returned to it’s original position in it’s original groove. Dots are placed where they won’t show in the assembled box, bottom of the strip and lower half of the groove.
The jig I use to cut the spline grooves is discussed elsewhere on this BLog. Here the first box side piece is clamped in the jig by the bench vise. This particular board is warped slightly and won’t lie flat against the jig so I use a couple of F clamps to pull it tight. If the grooves are not cut consistently, they won’t line up properly. Have to make sure the F clamps don’t interfere with any part of the plow plane.
In the video, Roy knifes the sides of the uncut groove at the exit point to control tearout from the plow plane. He guesses where the groove will end up and misses the mark quite a bit. My solution is to set the plane on the jig, put downward pressure on the main skate, and pull it back across the work piece. This leaves a mark across the miter and you can clearly see where to place the knife.
Hold the knife perpendicular to the miter surface and cut down both sides of the groove an eighth of an inch. It doesn’t hurt to knife edges at the beginning of the groove also, where the blade is dragged back across on the return stroke.
At first I was still getting exit tear out at the bottom of the groove (and Roy does as well), so I made this little chisel from eighth inch key stock. It’s sharpened at a 25 degree angle.
I set this in the groove in the stop block and give it a tap with a small hammer. Now the wood fibers are precut on all three sides of the groove and most plow plane tearout is eliminated.
With the board secured and all preparation complete, the actual plowing of the spline groove commences. Even with the jig it takes a lot of discipline to keep the plane moving in a perfectly straight line.
The 45 is cutting across end grain so the cutter has to be as sharp as I can get it. I will hone it after every other box (16 grooves). Also at the beginning and when the groove is cut about half way, I stop and wax the outside of the skate with paraffin.
The reward is a perfectly executed groove 1/8″ wide and 1/8″ deep with no tearout on either top or bottom edge.
I’m making four boxes with this project, so 31 more grooves to go!
And they are now all cut! One finished box and three sets of sides ready.