In cutting the saddle, the material is taken out of the under side of the upper log without disturbing the top surface of the bottom log. All the moisture thus drains out at the corner and, consequently, the wood is much less subject to decay than if other types of corners were used. The shrinkage in the outer area of the log’s circumference tends to open up the space between the logs. Finally, in the round-notch corner, one-half of the shrinkage between the logs is allowed to remain in the corner. The separation, therefore, is not as great as if each log had been cut down to the heartwood, a disadvantage common to most other types of corners.
The tools required to make a round-notch or saddle corner are: A pair of log dogs to hold the log in place, 10- or 12-inch wing dividers with pencil holder and level-bubble attachment, sharp ax, 2-inch gouge chisel with outside bevel, crosscut saw, spirit level, and plumb board. The framing of this corner, described in [figure 4], should be relatively easy.
Figure 5.—Chopping the notch in a saddle corner.
First, the bottom logs should be set in place on opposite sides of the foundation. Hew a flat face of 2 to 3 inches in width on the under side of the log where it rests on the foundation, so that it will lay in place. Then place the bottom log on each end-wall and accurately center it so that the inside face of all four logs is to the exact interior dimensions of the building. Dog the logs into place so they will not move while being marked for the corner notch. The wing divider is now set for one-half the diameter of the side log. With the lower leg of the divider resting on the side of the under log and the other leg, with the level-bubble uppermost, resting against the bottom of the upper log and directly above the lower log, start moving the divider upward, with a side motion, so that the lower leg follows the curvature of the under log. The pencil point of the upper leg makes a mark on the surface of the upper log which will be the intersection of the surfaces of the two logs when the notch has been cut from the upper one. Repeat this operation four times to mark all four sides of the corner. A little practice will make you adept at keeping the points of the divider perpendicular to each other.
After the notch has been marked at both ends of the log, turn it over on its back. It is a good idea to intensify the divider mark with an indelible pencil so that it will be easily followed. Chop the notch out roughly, as illustrated in [figure 5], then chip down as closely as possible to the mark, supplying the finishing touches with a gouge chisel. The finished notch should be cupped out just enough to allow the weight of the log to come on the outside edges, thus insuring a tight joint.
When the next side log is rolled into place, the dividers should be set apart for the width of the space between the top of the first and the bottom of the following log, and the marking repeated as before. If you wish to have the upper log “ride” the lower one a little, so that an especially tight joint is obtained, the dividers should be set a little wider apart than the space actually requires.
The dovetail, or box, corner (figs. [6] and [7]) is a strong corner, and considerable experience is required in order to make a neat-looking job. This type has several undesirable features: (1) The logs are apt to develop a wide crack because the corner is framed from the part of the log in which the least shrinkage occurs, and (2) since the logs are hewed down to form the corner, the wood has a tendency to collect and retain moisture which soon results in decay. Also, this corner detracts noticeably from the “loggy” appearance so characteristic and desirable in log structures. The drawings in [figure 6] show the most practical methods of marking and framing the dovetail, or box, corner.