Join Date: Mar 2012
Location: Beaumont, Texas
Preventing Plywood Splits with CS Holes
I am (still) building my shelving units for my home office. They are a very simple design with 3/4" oak plywood, oak strip edging in front, and a piece of plywood paneling for the back. No fancy joinery, I just plan to use three countersunk, brass colored screws to fasten the two sides to the top and bottom. And the back will be nailed into a 1/4" x 3/8" dado cut with a router after the top, bottom, and sides are assembled. I made some wall hung shelf units with some nice wood grained particleboard shelving using this basic design and I am trying to roughly match them. I can not get that particleboard shelving any longer so I was forced to move up to the oak.
I have the plywood cut into 12" (+/-) boards and the front edging strips glued on. I have cut the top, bottom, and sides for the first unit. My question is about drilling the holes for the screws. I got away with using a combination screw-form drill with the particleboard, but using it with the plywood worries me. I am afraid that those countersunk holes at 3/8" from the cut edges of the sides will tear the top layer of oak veneer, leaving a jagged edge.
After giving it some thought, I came up with the idea of using a Forstner bit to cut the outer edge of the countersink, perhaps only 1/64" deep or through the outer layer of veneer. Then using the combination bit to form the screw hole.
What do you think of that plan? Is there a better way?
Should I stain and varnish the pieces first to allow the varnish to help hold the veneer together? Should I use some masking tape over the hole locations? Any other suggestions?
If I do stain and varnish first, I know I will probably have to touch up the holes after drilling. Do you see any other problems?
And any suggestions for controlling the depth of the Forstner bit? This is too big to use the drill press so I am assuming I will be using a hand held drill, probably battery powered.