THE GLT7IXG OF WOOD 19 
used on most commercial edge joints. A shallow tongue-and-groove 
(one-eighth inch or less) is as useful in this respect as a deeper cut 
and is less vrasteful of lumber. 
The difficulties of making a perfect fit of the glued parts are still 
more pronounced in certain other types of joints. (Fig. 2.) In 
the serrate, dowel, mortise-and-tenon, dado tongue-and-rabbet, slip, 
and dovetail joints (fig. 2, C, F, G, H, I, and J) an imperfect fit 
of the parts results in only partial adhesion in the joints. In most 
of these joints, complete contact over poorly fit portions can not 
be obtained under ordinary gluing. Furthermore, pressure is often 
applied but momentarily in gluing such joints, and the glue does 
not have sufficient time to set. Careful machining of the parts of 
irregular-shaped joints is therefore necessary to obtain full strength 
and durability in service. 
PREPARATION OF VENEER FOR GLUING 
Yeneer for gluing is commonly cut by sawing, slicing, and rotary 
cutting (31, 53). Most veneer cut by sawing and slicing is glued, 
but perhaps less than half of the rotary-cut veneer is glued. The 
total quantity 1T of rotary-cut veneer glued, however, is larger than 
the combined amount of sawed and sliced stock glued. 
Sawed veneer is cut from flitches, usually for the purpose of get- 
ting a certain figure or grain. It is produced in long, narrow strips 
which are of substantially the same quality and appearance on both 
sides. Being thus equally firm and strong on both sides, alternate, 
pieces may be turned over in matching for figure such as in the faces 
of veneered panels. Quarterecl-oak veneer is cut chiefly by this 
process. Sawed veneer usually ranges in thickness from one-fourth 
to one-thirtieth of an inch. 
Sliced veneer is also cut to obtain a definite figure and is produced 
in the form of long, narrow strips or sheets. In the slicing process 
the veneer is sliced from a flitch by moving it against a heavy, 
stationary knife. The veneer is forced abruptly away from the 
flitch by the knife, thus causing fine checks or breaks on the knife 
side of the veneer. (PI. 3.) The checked side is called the open or 
loose side, and the other side is called the closed or tight side. The 
open side is likely to show defects in finishing and therefore should 
be the glue side whenever possible. In matching face stock where 
the open side of part of the sheets must be the finish side, the veneer 
must be well cut. Mahogany, walnut, Spanish cedar, oak, and a few 
other species are cut by the slicing process. Sliced veneer is cut in 
thicknesses ranging from about one-sixteenth to one one-hundred- 
and-twenty-fifth of an inch. 
Most rotary-cut veneer is produced in large sheets by revolving 
the log against a knife, flat-grain veneer being peeled off in a con- 
tinuous sheet very much like unrolling paper (31). The half-round 
process is used to produce highly figured veneer from stumps, burls, 
and other irregular parts of logs. (PL 2, B.) This process consists 
of placing off center in a lathe a part of a log and rotary cutting it 
into small sheets of veneer. All rotary-cut veneer has an open and 
17 In 1921, 87 per cent of all veneer manufactured was rotarv cut, 7.6 per cent sliced, 
and 5.4 per cent sawed, and in 1923 the percentages were 92, 3.3, and 4.7, respectively (54). 
