30 a.
A beveled shoulder joint is used in Pbce of the beveled»iap joint where it Htsired to conceal the angled tenon
the diagonal member. Fk
30 .
Dimensions. A good rule for calculating the proper dimensions of a tenon is to proportion it so that it is one third the thickness of the rail of which it is a part, and of a width not more than six times its thickness. Wider tenons weaken the mortise and should be divided into double mortise and tenons.
In designing furniture, or following drawings or instructions that omit the dimensions of tenons, the following proportions are recommended:
Rail thickness, in inches H и 12
Tenon thickness, in inches 516 и и
Tenon length, in inches I гУл i
Drawboring. A tight mortise and tenon joint can be assured without the use of glue and clamps by recourse to a jointing operation known as "drawboring." This is accomplished by boring the holes for the pins, pegs or dowels through the empty mortise, after which the tenon is inserted and marked through the center points of the holes.
When the tenon is withdrawn from the mortise, however, the holes are drilled slightly nearer the tenon's shoulders than indicated by the marks. By driving
in a tapered peg or pin, the tenon will be drawn up tightly against its shoulders and held there firmly, without recourse to glue, as shown in the cutout, Figure 1.30 b.
Corner Joints. (Figure 1.31). The simplest joint for uniting two members on edge at right angles is the rabbet joint, most often encountered where a plywood panel is joined to the back of a cabinet by nails, screws, or a small molding. It is also foun