I never seem to have the right dowel. If it’s the correct diameter, it’s the wrong kind of wood. Rather than stocking dowels of every size and species, I make my own, using a tool that’s probably been around since the Iron Age.
My dowel maker is a 1/4-in. steel plate with holes that decrease in diameter by 1/64-in. increments. Driving a square blank through the series of holes produces a round dowel that matches the smallest diameter. The blank should be no larger than the largest hole; shaving one end to a point makes starting easier. The dowel is roughly shaped at first; successive passes refine it. Dowels made this way are perfectly sized, but they often show some tear-out. They also have to be made in short sections; hammering slender blanks that are longer than 12 in. causes too much deflection.
Each hole is drilled through from the top and then counterbored 1/64-in. oversize from the bottom. Stop the counterbore 1/16 in. short, so all that remains of the original hole is a 1/16-in.-wide lip at the top. This lip provides the cutting edge. The counterbore provides clearance for the dowel.
To drill accurately sized holes, you must firmly clamp the plate to your drill-press table and your drill bits have to be sharp. Use a centerpunch to locate each hole and keep the drill bit from wandering. Operate the press at 1,000 rpm (slower for 7/16-in. or larger bits) and use cutting oil while you drill.
Flattening and polishing the top surface creates cutting edges around the holes. For this step, you can use your sharpening stones or sandpaper adhered to a flat surface.