Building the Traditional Hewn-Log Home

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Want that in English? OK: Since R is 2" (again, that's the vertical distance from the upper to the lower edge of the slanted surface of the top notch), then the amount of rise at the log's horizontal center point (halfway across) would be half of that, or 1". Thus, to adjust the upper notch measurement so that it will be accurate at the inside face of the log, we simply say that U (upper notch measurement) equals D (notch depth) plus half R (rise).

Returning to algebraic lingo, we'd have

U = 2-1/2 + 1/2 (2) = 3-1/2.

These two formulas tell us that the uppermost point of the lower notch in this round would be marked 2-1/2" below the centerline on the inner face-while the top (inner) edge of the upper notch would be marked 3-1/2" above the centerline. (Hint: When using 6°-thick logs and a pitch of 1:3, you can do away with the second formula entirely by remembering that the measurement for the upper notch will always be 1" greater than the measurement for the lower notch.)

NOTCH LAYOUT

With the headwork done, it's time for the hands to take over. To eliminate confusion when marking and cutting notches, place your sawhorses alongside the wall that will receive the timber you're working on, then position the log on the horses—end for end—just as it will go on the wall. That way you won't cut your notches upside down and backwards, as a couple of students at the Nantahala workshop did on their first try!

Here's Peter's 16-step outline for marking and cutting half-dovetail notches:

[1] Lay a log on the sawhorses with the inside face up. To determine which is the inside face, remember that the crown always goes up when a log is put in place on a wall-and that butts and tips alternate with each round.

[2] About a foot in from each end of the log, at a point that's free of any atypical bulges, measure and mark the vertical center of the inner face. To find the center, hang the short leg of the square over one side of the log and pick an inch mark that you estimate to be near the center of the face (for example's sake, let's say you choose the 6" mark), and mark this spot on the log. Now turn the square around, hang it from the opposite side of the log, and make a second mark at the same (6") line on the square. The midpoint between these two marks is the vertical center of the log.

[3] Using the vertical center marks at each end of the log as guides, chalk a centerline along the inside face of the log.

[4] For the next step, one end of the log must be square. If neither end is square, position the long leg of a framing square along the centerline and draw a perpendicular line across the face of the log a couple of inches in from the end to be squared, then extend this line around the rounded surface, using a piece of paper as a flexible straightedge. Following the guidelines, cut the end off.

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