Experimenting with Tapered Stopped Sliding Dovetails
Note: To read all of the posts in this series, click here.
I’m working on a small project using reclaimed American Chestnut lumber that was salvaged from an old Appalachian barn. For the back story on my acquisition of this lumber, and the driver for making this particular project, you can read this post. When I left off at the end of that last post, I had finished the process of milling and edge gluing some of the boards to make wider panels.
The wider panels are needed for the top, sides, shelf and back of the piece. Each of these panels had to be glued up from two narrower boards as I did not have a single board that was wide enough for these parts. For the dividers, I had a piece that was just wide enough to get them out of a single board.
For such a simple piece, I could have just used nails, or a combination of rabbets, dados and nails to join the parts together. The piece will not have to support much weight after all, and cut nails are extremely strong and resistant to pulling out. However, I have wanted to play with a sliding dovetail plane that I acquired last year, and this project seemed like the perfect opportunity to do so. I don’t use full length sliding dovetails in my work very often, so this piece would be a fun way to experiment with them, and play with my new plane. To add a bit more visual interest and challenge to the piece, I decided to stagger the front edges of the components, necessitating the use of a stopped joint.
After sizing the top, shelf, and side panels, I proceeded to lay out the female half of the joint. I intended to use a tapered stopped sliding dovetail to make all of the joints easier to fit. So before I started laying out the joinery, I penciled in the location of each piece in the final assembly. Not only does this provide a good visual representation of the finished dimensions of the cubbies, it helps to visualize the taper of the finished joint to make sure that it tapers in the right direction. Being a stopped joint, only able to go together from one end, if the taper gets cut backwards, the joint will not go together.
After laying out the angle of the dovetail on the back edge, the narrow portion of the tail is transferred to the front edge of the joint. In this case, the socket stops 3/4″ from the front edge of the board. The joint is tapered on one side only, to make fitting the joint easier. So one side of the socket is laid out square to the back edge of the board. The other side of the socket tapers in by 1/16″ from the back edge to the front edge. It is critical to label the side of the socket that tapers on every joint so that the mating tail can be tapered on the same side. If the taper gets reversed between the male and female sides of the joint, the parts will not go together square.
With the layout complete, the side walls of the tapered dovetail socket can be sawn. To accomplish this task with a stopped joint, like this one, a hole must first be bored and chopped at the stopped end of the joint to give the saw a place to exit the cut. I bore the hole with an undersized auger bit. Then the hole is chopped square and the sides are chopped at the approximate angle of the dovetail. This hole gives the saw a place to exit the cut and dump the sawdust. A batten is clamped to the piece along the cut line to help guide the saw as the cut is made. I typically just hold the saw at the correct angle by eye, but the batten could also be cut at the correct angle to help position the saw at the correct angle.
After sawing the sides of the sockets, the majority of the material can be removed with a chisel. To make this job easier I saw a kerf down the center of the waste. The socket is wider at the bottom than it is at the top, so the waste can get wedged in the socket while it is being removed. If the chisel is driven too hard against the wedge shaped waste, the top of the dovetail socket can split off. By sawing a kerf through the center of the waste, and using a narrow chisel to chop out the waste, damaging the top of the dovetail socket can be avoided, or at least minimized. Once the majority of the waste is removed with the chisel, a router plane cleans up the rest.
The male part of the sliding dovetail is the easy half to cut, if you have a sliding dovetail plane. This plane is very similar to a moving fillester plane, except instead of having a sole that is square to the side of the plane, the sole is angled to the side of the plane, allowing a rabbet with an angle less than 90 degrees to be planed on the board. As with all fenced planes, I don’t completely trust the fence not to move in use, so I still lay out the shoulder of the joint with a marking gauge before I start planing so that I have a point of reference if the fence happens to shift. The plane has a nicker to score the shoulder for cross grain use, and makes short work of sinking, tapering, and tuning the tapered sliding dovetail. As with the sockets, only one side of the dovetail is tapered.
The male half of the joint can be cut without a sliding dovetail plane. Doing so requires the two shoulders to first be cut with a saw. The material outside of the saw cut is then pared away with a chisel, following layout lines to guide the dovetail shape. Roy Underhill has demonstrated this method in plenty of episodes of The Woodwright’s Shop.
The only other joinery required before assembly are three rabbets for the back to fit in. The rabbets in the back edges of the sides are easy to make with just a rabbet plane because they are through rabbets. However, the rabbet in the back of the top shelf is a stopped rabbet, so it cannot simply be planed. First, clearance needs to be made at the ends of the joint for the rabbet plane to start and finish in. I did this by chopping away the material at the ends of the rabbet with a chisel and router plane before switching to the rabbet plane to remove the material in the center.
After completing all of the joinery, the only detail left to add before the piece could be cleaned up and assembled was the quarter round cutout at the bottoms of the sides. This was easily laid out with a compass (it’s a 4″ radius arc), sawn with a turning saw, and cleaned up with a rasp and card scraper.
The parts were cleaned up with a smoothing plane and some hand sanding with 220 grit paper. At that point they were ready for glue-up. However, I decided to do something else with this piece that I don’t often do, pre-finish before assembly.
