Dowels are considered to be one of the strongest methods for bonding wood. A dowel which is correctly placed can last a lifetime if it is correctly installed. For the installation process there things are important: the positioning, the drill bit and the method.
First thing: method
For placing dowels you can use a free hand drill, without the help of a jig or a drill press. But know that it would be very difficult to drill the hole straight and therefore is not warmly recommended. However using a drill press is recommended but not always feasible because the depth of the hole could be compromised due to the lack of possibility of placing large or long pieces on the drill press. And the best for the last – a handheld doweling jig is definitely the best way to drill your dowel holes. It can align the bit and hold it steady while you drill. The last to drills are recommended also for drilling dowel holes at an angle.
Choose the best bit
There are a few different types of drill that are all suitable for use with dowelling projects.
Brad point bits which are also known as lip and spur bit or dowelling bits. These are the most common types of drill bits used for dowelling (as their name already suggests) and the most accurate ones. They have a sharp point at the end of the bit, and they do not stick out much further than the cutting edge of the drill bit.
Spade bits are the next option. They are flat and have a triangular shaped point that makes a small hole before the edges of the ‘spade’ come into contact with the wood surface.
Auger bits are also good. They are thin, have a sharp tip and are shaped like a corkscrew which makes it easy for wood to be removed during the drilling process.
The Forstner bit is similar to a brad point but sharpened to a higher degree, with more accuracy. It cuts smoother and cleaner than a brad-point bit but since it has no spirals and the shaft is narrow, it won’t work with a doweling jig. The Forstner bit is the best choice when you have the option of using a drill press.
The general rule of thumb is to select a drill bit diameter that matches the dowel. For example, if you’re using a 3/8-inch-diameter, 3-inch-long dowel — the most common for 3/4-inch wood — select a 3/8-inch bit.
Drilling a dowel hole
Mark the center of the holes with an X and then punch a small divot in the center of the X with a center punch, a nail or some other sharp tool. Measure the length of the dowel, divide it in half and wrap tape around the bit at the measurement. Clamp the work piece to a tabletop or a bench and then insert a 3/8-inch dowel in the doweling jig. Center the sleeve over the “X” and tighten the clamp. Begin drilling and apply pressure to the drill until the tape reaches the wood, which is your sign to stop.
Drilling at an angle
Drilling dowel holes at an angle is frequently required. You have the jig which will hold the working piece in the required angular position. Angular drilling for screw-pocket holes requires no calculation. A guide board with one edge cut at 15 degrees bevel is clamped to the table so that the drill makes a hole at the extreme edge of the bevel. So the basic rule in drilling at an angle is that the work must be square with the table. Dowels almost always are along the surface in one piece of wood, and across the surface in the part it joins to. Also please take a look at the versatile angle dowel joints.