Dovetail Anatomy 101Comments (0)
This article is from Issue 95 of Woodcraft Magazine.
Q: Depending on the drawer opening I need to suit, I’m discovering that the fixed template on my new dovetail jig doesn’t always allow for terminating a joint at each end with a half-pin, as in traditional dovetail drawer joinery. Is it a problem if a joint ends on a half-tail instead?
Mark Clemmons Cincinnati, Ohio
A: The answer lies in the joint’s inherent grain direction, and in your ability to size the joint elements.
First off, consider that the perimeter is where the most stress occurs with dovetailed corner joints in drawers and cabinets. If a joint is going to fail, it’ll happen at the outer edges. That’s why it’s a good idea to cluster more pins at the corners to keep these areas as strong as possible.
The reason for half-pins and not half-tails at the corners is, again, for strength: The grain in a half-pin runs straight, as opposed to a half-tail where the grain is truncated by the angle of the tail at its inside corner, making this area short-grain and subject to breaking.
As you’ve discovered, the fixed layout of a dovetail jig template doesn’t always allow you to end with half-pins of sufficient width. As a rule of thumb, leave at least 1⁄4" of width at the narrowest part of a half pin for joint strength. When this isn’t possible, switch your layout to a sufficiently wide half-pin and a correspondingly wide half-tail. Keep in mind that a half-tail needs extra width at its narrowest section, so keep this area as wide as possible for strength.
Finally, if you’ve decided to lay out one half-pin and one half-tail, position the half-pin at the top of the drawer or at the front of the case, and leave the half-tail at the bottom or back where it’s less likely to be seen.
Although a dovetail jig affords speedy production, I’m a big fan of hand-cut dovetails for their hand-made look and feel, the ability to fashion any desired dovetail angle, and the option to lay out half-pins at the ends every time.
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