Sunday, December 28, 2008

Half Blind Dovetails

I believe the two most important skills in handcutting dovetails are careful layout and the ability to saw a straight line.

Regarding the feather-ruffling question: Pins or Tails?

My answer is: Yes.

For a box or drawer that will have fat pins, I cut tails first. Cutting the tails first allows you to saw the two tail boards at one time. Plus, transferring layout lines from tails to pins is easier than vice versa.

For a delicate project with skinny, English-style dovetails, I cut pins first. With thin pins, it's very difficult (and in some cases, impossible) to transfer layout lines from tails to pins, so cutting pins first makes sense.

That being said, I'm cutting tails first for the drawer on the sawbuck table, with through dovetails at the back and half blind at the front.

The drawer will have angled sides, so the width at the top is 15" and the width at the bottom is 13". I believe I've mentioned my geometry-challenged brain before.*

My tool arsenal includes: dovetail saw, jeweler's saw, various chisels, guide block, plane blade, pencil, ruler, dovetail marker, clamps, marking gauge, mallet, and tiny square.

I call the technique: Dovetails with Training Wheels.

The training wheels are in the form of a guide block that's used to keep the chisel perpendicular to the workpiece. This ensures that the area that's removed between tails & pins will be flat. Some people like to undercut this area so pins and tails seat exactly to the guide lines, but a guide block removes this potential problem.

Once I've cut the tails, I use a bevel-edged pencil to transfer the outlines to the adjoining board, but you can also use a marking knife. Take care to make precise marks when you transfer these lines. When you saw the waste, cut right to the line (the line will just barely be sawn away when you've finished cutting). The more accurate the layout and cut, the less paring (if any) you'll have to do to fit the boards together.

*A friend accused me of never posting anything that I've screwed up. So here it is. Because I'm missing a math gene, my boards are not aligned along the top and bottom edges.

To transfer the tails' outlines to the front board, I aligned the top and bottom edges as I would with a square project. But bevelled sides require that the boards be offset when you transfer your marks.

I still don't know the equation to figure out the measurement for the offset, but fortunately the depth doesn't matter in this project, so I can plane the top and bottom edges to match.

There's also a gap in the top pin. But it's nothing that a little well-crammed wax can't fix once the project is finished.