Dowel centres are indispensable tools that master craftsmen use when building fine furniture. A dowel centre pinpoints an otherwise invisible location for a dowel. A dowel centre pinpoints the location on a separate piece of wood by masquerading as a dowel itself. Dowel centres are often used on fine furniture that need perfect alignment. There are as many sizes of dowel centres as there are drill bits. For this reason, the ability to make your own homemade dowel centre is a huge benefit.
Dry fit and select size
When your project is ready for dowels, assemble or "dry fit," two of your pieces together and decide what size dowel you'll need. You might be able to use the same size dowel through the entire project.
Mark the location of your dowel hole. Get out your drill and with the size of bit you have selected for your dowel; drill it in one piece of wood only.
Now select a 3/4-inch bolt from your toolbox, the larger the diameter the better---but smaller than the hole that you drilled in the wood. Using a pair of pliers and a grinder, sharpen the HEAD of the bolt slightly, leaving enough of the bolt head to retain a washer. After it cools, thread a washer on it bigger than your dowel hole.
Size and centre
Now wrap 1/2-inch masking tape around the base of the bolt, just below the washer. Place the bolt in the hole that you drilled. If it's too loose, add more tape, until the screw slides into place with just enough force to keep it there. You should have the sharpened end of the bolt sticking out of the hole, dead centre. This is your dowel centre for the receiver hole to be drilled in the opposite piece of wood.
Apply and mark
Carefully slide the two pieces of wood together in the EXACT location where you want them to be dowelled. When the sharpened tip touches the piece of wood, tap it slightly--it will leave a tiny mark. This is where you drill.