Dowel joints are one of the easiest - and cheapest - methods of fastening two pieces of wood together. The technique is ideal for joining two flat pieces together to form a larger flat surface (as used in the TV cabinet project).
Take two pieces of equal length wood. Decide now which side will be the top and which the bottom for each piece and mark the top side of each so that you do not forget.
Clamp both pieces together, one on top of the other, with the bottoms face to face in the middle. When clamping, ensure that the two surfaces along which you plan to join these pieces of wood are level with each other (see diagram one).
Draw a line down the middle of each surface to be joined. This must be exactly the same on both pieces of wood, otherwise when they are joined there will be a step at the join. Once this line has been drawn, using a set square mark lines across the grain of the wood (see second diagram). The intersection of the length and width lines show where the dowel holes will be drawn. There is no hard and fast rule for how many dowels should be used. However, the heavier the weight of whatever will be on the surface, the more dowels should be used. Typically, one dowel per foot is a good rule (with a minimum of two).
Once these lines have been drawn you can then proceed to drill the holes at the marked intersections. The drill bit used should match the diameter of the dowel being used, thus ensuring a tight fit. As for the dowel itself, you can either make your own small dowels from a longer length, or you can buy dowel made specifically for this reason. The latter option is a far better solution, as the small dowels are beveled at the ends to make it easier to but them in the holes, and are ribbed to allow the glue to bond more efficiently. Each hole should be just over half as deep as the length of the dowel being used.
Once the holes have been drilled, glue one end of each dowel into the holes in the first piece of wood. Then place glue along the full length of the second piece, ensuring that some glue falls into each of the holes.
Unclamp the two pieces and push them together, ensuring that the two top markings are facing up. Once done, clamp tightly overnight. Be careful when you clamp them to make sure that both pieces remain flat and do not try and warp upwards. To avoid this, it may be necessary to clamp the entire piece down to a flat surface.