A Domino® joiner is a specialized hand power tool for woodworkers that cuts small slots into wood stock as part of a system of joining two pieces of wood together in mortise and tenon joinery. A relative newcomer to the power hand joiner marketplace, the Domino® joiner was developed by a German company called Festool and introduced to the woodworking market in 2006. It joined the high end of a very competitive biscuit joiner market.
Among the strongest joints in woodworking, mortise and tenon joints are a simple and very strong way of joining pieces of wood together. At its most elementary, a mortise is a slot or hole cut into one piece of wood, and a tenon is another piece of wood that fits into the slot. Biscuit joinery is a type of mortise-and-tenon joinery that involves cutting mortises into the edges of two pieces of wood, then gluing a small tenon of wood — the "biscuit" — into first one, and then the matching slot. Traditional woodworking biscuits are ovoid-shaped flat pieces of birch, which are very highly compressed so that they expand into the mortise upon contact with the moisture in the glue. Domino® biscuits are available in five sizes, from approximately 0.2 by 0.75 by 1.2 inches (5 by 19 by 30 mm) to 0.4 by 0.95 by 1.95 inches (10 by 24 by 50 mm) and look like dominos, only smaller; hence the name.
A traditional biscuit joiner cuts mortises with a spinning blade that carves an arc into the workpiece to a depth set by the operator. It's the arc that makes the traditional ovoid biscuit a perfect fit. A Domino® joiner cuts with a very sharp router bit that not only plunges into the stock to be cut, but also sweeps from side to side of the cut, squaring off the edges rather than leaving an arc. The depth of the cut is controlled by the operator, and the rectangular shape of the cut accommodates the rectangular Domino® biscuits, which are proprietary.
A major drawback to the Domino® joiner is the price, which, depending on the model and accessories, can by three to four times that of traditional biscuit joiners in the marketplace. Those who've used both products attest to the advantages of using the Domino® joiner, especially the speed with which workpieces can be set up for joining because of the indexing and registration capabilities the tool has. By contrast, when using traditional biscuit joiners, individual slots have to be measured and marked off.
The choice of whether to acquire a traditional biscuit joiner or the more costly Domino® joiner may ultimately lie with the nature of the work being performed. Those for whom woodworking is a hobby, and who aren't facing the deadlines and time constraints of a production shop, will likely be satisfied with the highly accurate traditional biscuit joiner. Those professionally involved in the production of cabinets and furniture, however, have a much greater need for speed without sacrificing accuracy, and will likely see their production levels increased by the Domino® joiner.