Dowel reinforced butt joint

The dowel reinforced butt joint or simply dowel joint has been a very common method of reinforcing butt joints in furniture for years. They are common in both frame and carcase construction. Dowel joints are popular in chairs, cabinets, panels and tabletops. They are also used to assist with alignment during glue up.

The technique consists of cutting the members to size and then drilling a series of holes in the joint surface of each member. Holes are often drilled with the assistance of a dowelling jig which aids in accurate hole placement — accuracy is paramount in this technique to ensure members line up perfectly in the completed joint. The holes are drilled such that there are corresponding holes in each member into which short dowels are inserted with some glue. The joint is brought together and clamped until the glue has dried.

This produces a joint which is much stronger than a butt joint without reinforcement. The dowels offer some holding strength even after the glue has deteriorated. Over time, dowels may shrink and become loose. They take on an oval shape in section owing to the different rate at which wood moves with different orientations of the grain. Loose dowels allow the joint to flex, although it may not fall apart. This phenomenon is evident in creaking chairs and wobbling book cases. For this reason, dowel joints are not preferred for high-quality furniture. Use for: A variation of the dowel method for reinforcement is the use of a Miller dowel in place of the usual straight cylindrical dowel. The Miller dowel is a stepped dowel and is drilled with a special stepped drill bit. It is drilled from the outside face of the frame piece to be joined and therefore generally leaves an exposed dowel protruding after glue dries, and the excess dowell head is thus usually flush cut. The advantages of the special dowel are documented in various media promoting the method, but one advantage that should not be overlooked is speed of assembly. The butt joint can often be joined temporarily and sometimes more accurately with simply glue, allowing faster set up than the usual tedious alignment procedures mentioned above. After the glue dries one or more Miller dowels are then used to reinforce the joint. Dowel trimming and sanding of the surface, followed by normal finishing then proceed in the usual manner. The blind alignment problems of floating dowels are virtually eliminated by the use of the Miller dowel. Not all projects are appropriate for the stepped dowel method if an exposed dowel end is not visually acceptable, however.
 * Frame joinery (e.g. face frames, web frames, door frames, table legs to aprons, chair legs)
 * Cabinet carcase construction (e.g. carcase sides to top and bottom, fixed shelving/partitions)
 * Panel assembly (for alignment)