The following is excerpted from “The Joiner & Cabinet Maker,” by Anonymous, Christopher Schwarz and Joel Moskowitz, from the chapter on making the dovetailed schoolbox.
In this chapter, as with the other projects in the book, Chris builds “alongside” young Thomas, the main character in the charming 1839 fictional account of an apprentice in a rural shop that builds everything from built-ins to more elaborate veneered casework. The book was written to guide young people who might be considering a life in the joinery or cabinetmaking trades, and every page is filled with surprises. You can read more about it here.
To understand how little that is certain with dovetails, let’s take an abbreviated journey through the literature. I promise to be quick like a bunny. Charles H. Hayward, the mid-20th-century pope of hand-cut joinery, suggests three slopes: Use 12° for coarse work. Use 10° or 7° for decorative dovetails. There is no advice on hardwoods vs. softwoods. F.E. Hoard and A.W. Marlow, the authors of the 1952 tome “The Cabinetmaker’s Treasury,” say you should use 15°. Period.
“Audel’s Carpenter’s Guide,” an early 20th-century technical manual, says that 7.5° is for an exposed joint and 10° is right for “heavier work.” No advice on hardwoods vs. softwoods. “Modern Practical Joinery,” the 1902 book by George Ellis, recommends 10° for all joints, as does Paul Hasluck in his 1903 “The Handyman’s Book.” So at least among our dearly departed dovetailers, the advice is to use shallow angles for joints that show and steeper angles if your work is coarse, heavy or hidden. Or just to use one angle and be done with it.
At least in my library, the advice on softwoods and hardwoods seems to become more common with modern writing. Percy Blandford, who has been writing about woodworking for a long time, writes in “The Woodworker’s Bible” that any angle between 7.5° and 10° is acceptable. The ideal, he says, is 8.5° for softwoods and 7.5° when joining hardwoods.
One Wednesday morning as I toiled with these old books, I went into the shop and laid out and cut a bunch of these dovetails. I ignored the really shallow slopes because I wanted to adopt something more angular. The 10° dovetails looked OK. The 12° dovetails looked better. The 14° tails looked better still. And the 15° looked good as well. Whatever angle you use for your joint, you can rest easy knowing that someone out there (living or dead) thinks you are doing the right thing.
One thing is certain: As dovetails have become somewhat of a cultish joint (a 20th-century phenomenon), their angles have gotten bolder. As Thomas’s slope looked too shallow for my eye, I chose 14°.