Mortisers

Mortisers are woodworking machines or hand tools used to cut mortises—rectangular or square holes that accept joinery such as mortise-and-tenon joints. They are designed to produce clean, accurate cavities in wood with consistent dimensions, improving alignment and strength in furniture, cabinetry, and framing work.

There are several forms of mortisers. Hollow-chisel mortisers use a hollow, square- or rectangular-chisel assembly that cuts the sides of the mortise as the tool passes vertically through the stock. A moving square-edged mortising chisel then squares the ends and closes the opening to the desired depth. This type is common in shop work for producing medium to large mortises with good repeatability. Drill-mortisers, often built as attachments for a drill press or as stand-alone units, cut the bulk of the material with a drill bit and then use a mortising chisel to square the corners. Benchtop and floor-standing models vary in size and are chosen to suit the workpiece dimensions and required mortise width.

Mortising capacity is described by mortise width, depth, and the length of travel. Common widths range from about 1/4 inch to 1 inch (approximately 6 to 25 mm), with depths typically 2 to 4 inches or more on larger machines. When used with a mortise-and-tenon joint, precision in alignment and square corners is essential for a tight, durable fit.

Safety and setup emphasize securing the workpiece, using guides or jigs to maintain square alignment, and making clean, controlled cuts to reduce tear-out. Alternatives for mortising include hand mortise chisels and routers equipped with mortising jigs, but machine mortisers offer speed and repeatability for production work.