I learned this trick way back when I transformed countless wooden knobs into cupboard turns. I needed to drill the rounded portion or tenon of the knob – the part that generally was glued into the door or drawer – so I could insert a short section of dowel that would extend through the door. That dowel would have a wooden finger attached that would turn down onto a small wedge attached to the backside of the door. I could have simply purchased the turns, but the knob design seldom matched the other wooden knobs used on the piece.
Today, while using more brass than wood for pulls, knobs and turns, I use the technique only sparingly. But it’s a great technique when you need it.
Begin by drilling a hole into a scrap that is sized to the diameter of the rounded object; generally that would be the knob tenon when making a cupboard turn. In this case, I’m drilling a hole in the center of a dowel, so in my example, I’m drilling the diameter of the dowel (shown at right). Drill the hole deep enough to allow the base of the knob, if that’s what you’re drilling, to sit flat against the scrap. (You should do this with a drill press to make sure the holes are straight and true.)
Change drill bits to the diameter of you’re new hole, and drill clear through the scrap using the center of the first hole as a guide to align the second hole. The idea is that the first hole holds the piece to be drilled in place and the second hole locates the exact point of the new hole. To put this in terms of drilling out for cupboard turns, the knobs would have a 1/2″-diameter tenon into which I would fit a 7/16″-diameter post. There was little room for anything but exact alignment.
To use the setup, insert the tenon, or short piece of dowel in this case, into the appropriate diameter hole, align the drill bit with the second diameter hole (as shown at the left) and drill down. It’s that simple. Plus, every time you use the jig, the results are the same (as shown in the opening photo). And it doesn’t matter what diameters you use, as long as the second hole is smaller.
Put this trick into your pocket. Some day it will come in handy.
Build Something Great!