* Transfer the hinge
mortise locations onto the door by setting the door into the opening and shimming up the bottom until the door fits tight against the top molding.
Structural tests were conducted to determine the strength and deflection characteristics of an 8 by 10 foot light-timber barn frame constructed with 3.5-inch square Douglas-fir members and round
mortise and tenon joints.
Overall, these performance tests tend to indicate that for square members, the increased bending moment capacity of round
mortise and tenon joints with shoulders is functionally related to the ratio of W/D where D is the diameter of the tenon and W is the width of the member in the plane of the bending moment (hereafter referred to as a "stretcher").
Kamenicky (1975) investigated the flexibility of spruce and beech
mortise and tenon joints and determined flexibility factors to characterize their behavior.
Dupont (1963) showed that optimum joint moment capacity is obtained when glue is applied both to the tenon and to the sides of the
mortise. Also, wood moisture contents of 7 to 9 percent are most appropriate for fabricating these joints.
Adhesive-based, shrink fit, and cross-pinned round
mortise and tenon joints have been used in furniture construction for centuries, but the withdrawal capacities of these joints remain largely unknown.
In the case of round
mortise and tenon joints, however, cross-pins might actually reduce the bending moment capacity of the joints since they could induce parallel to grain shear failures in the tenons.
For example, all tests with an end distance of 7D for eastern white pine failed in a ductile manner as a result of peg failure (i.e., no splitting of
mortise or tenon members was observed).
Given the above results, the maximum possible practical distance was maintained between
mortises for side rails and the
mortises for front and back rails in the chair shown in Figure 1, in most instances, a spacing of 1-3/8 inches.
STEP 5: Mark the width of the
mortises with the marking gauge.
Mortise and tenons joint geometry has a significant effect on the strength of those particular joints (Tankut and Tankut,2005).
So now, how to cut the
mortises? I purchased a square-hole drill rig, feeling pretty smug about having a project that I could fully justify and thereby amortize the expense.
