I’ve been cutting a lot of large-scale sliding dovetails and rabbets lately. And when these housed joints get to a certain size (think of a dovetail socket that is 4” wide and 30” long) it’s much more efficient to saw out the walls by hand.
When I need the rabbets or sliding dovetails to be bang-on, I clamp a batten to my work to guide the saw. I use a vertical batten for rabbets and an angled one for sliding dovetails.
The only tricky part about the joint is keeping the sawplate against the batten. Usually I use my fingers, but it’s easy to get the tips of your fingers shredded if you aren’t careful.
Then I saw a little trick in an old English woodworking magazine that turned on a lightbulb: Use a block of wood to press the sawplate to the batten. I started doing this in June, and it immediately made the joint easier to cut and more accurate.
Give it a try.
— Christopher Schwarz