The round-notch, or saddle, corner (fig. 2) is generally considered the
most satisfactory from every standpoint. This type of corner gives the
most distinctive appearance because the logs project sufficiently beyond
the corner not to appear dubbed off (fig. 3). It is a good, self-locking,
mechanical joint, relatively easy to construct, and holds the logs
rigidly in place.
[Illustration: Figure 4.--Method of marking saddle corners.]
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.
[Illustration: 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.