CHAPTER 5, LESSON 4 of 5
GOAL: To understand the basic features and types of dovetail joints and to learn how to design and lay out a dovetail joint.
Few aspects of woodworking evoke as much emotion as the dovetail joint, and its strength and durability are demonstrated by its survival on so many pieces of old furniture. Learning to make this storied joint involves learning the anatomy of the dovetail, as well as how to design and lay out the joint for maximum beauty and strength. This lesson will provide an introduction to the dovetail joint and describe the process of designing and marking the joint.
| Marking out a through dovetail joint |
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| A dovetail is laid out according to ratio of width to length. Set your sliding bevel to the layout from your measurements.
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Set the cutting gauge 1/32" less than the thickness of the pin piece. |
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| Knife all the shoulder lines with the cutting gauge.
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Lay out the tails by squaring across the top with pencil. Mark the slope with pencil and sliding bevel. Extend the pencil guidelines well below the shoulder lines to help guide the dovetail saw. |
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| Mark the pins from the tails with a marking knife. |
Square down cutting guidelines from the pin marks. |
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| Dovetail layout is an important step in mastering the joint. In this case, small pins have been chosen to create an elegant appearance. Transfer this pattern to your stock for best results.
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| Through dovetail: It’s usually the first dovetail joint a woodworker learns to make.
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Single-lap dovetail: It’s commonly used in making drawers, to join the front to the sides. |
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| Double-lap dovetail: A thin strip of end grain shows that this joint is hidden inside. |
Secret-miter dovetail: It’s used when the wood is so beautiful that a visible joint is undesirable. |
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| Four options for the corners of the joint |
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| Half pin on outer edge. |
Half tail on outer edge. |
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| Half pin with corner miter.
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Half tail with corner miter.
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As shown in the illustration above, a dovetail joint consists of two interlocking pieces — one cut with tails and one cut with pins. The joint is inherently strong because these interlocking parts also provide significant glue surface.With this strength comes a requirement for exactness, however, because each joint is plainly visible, and any mistake or attempt to doctor a gap is equally visible.
Besides deciding which type of dovetail joint to use, there are two primary things to consider in designing a dovetail: the slope or angle of the tails and pins and the relative size of the tails and the pins. The slope, measured as a ratio of width to length, is important. If it’s too great, the corners of the tails are vulnerable to breaking off because of fragile short grain. If there’s too little slope, the dovetail looks like a bad finger joint. A slope between 1:4 and 1:5 makes for an elegant solution. The second aspect of design to consider is the relative size of pins and tails. Over time, woodworkers have come to accept that the appearance of the joint is more pleasing when the tails are made larger than the pins.
It’s also important to note that the tails go on the longer side of a rectangular case.
In planning the joints for a project, it’s a good idea to spend some time drawing different layouts before committing to the work. If you make the drawings full-size and as accurately as possible, they can serve as a working drawing, as shown in the illustration at the right. Resist the urge to begin by laying out the joints directly on the wood.
As shown in the illustration at right, there are four basic types of dovetail joints: the through dovetail, the single-lap dovetail, the double-lap dovetail and the secret-miter dovetail. Each has features that recommend it for particular situations.
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