Impossible dovetail joint with curved pins and tails

Impossible dovetail joint with curved pins and tails

Let’s see how to make a curved dovetail joint on the router table. A variant I came up with to make from the typical impossible dovetail joint. These joints can be made in the head of the wood strips, or in pieces with more or less a square section. And the main feature is that, at first glance, they seem impossible not only to make but both to assemble and disassemble.

I am going to make this impossible dovetail joint in the head of two 6.5cm square section wood strips. And to make it I need to improvise a simple woodworking jig to route circles in the head of the wood pieces on the table router.

Pivot pin for routing in circles

So, the first thing I had to do was to make a kind of box or wood prism inside which the wood piece to be routed fits perfectly. And in one corner of that prism I put a nail point that serves as a pivot pin for routing in a circle.

Circle routing jig

The circle routing jig is completed with a plywood board that is hold with clamps on the router table. In this board there is a groove that allows the dovetail router bit to move inside the board.

How to route curves on the router table

So, I pin the nail that serves as the pivot pin into position in that board, I press the plywood prism together with the workpiece against the board, and I turn both to route a quarter circle in the head of the workpiece.

Stops for routing on the router table

Then I move the board between the two stops that I have put on the side fence of the router table.

Route a quarter-circle on the head of the workpiece

And I make a second routing. So, by routing twice a quarter circle in the head of the workpieces, I have the sockets between the pins into which the tails will fit later (actually in this impossible dovetail joint the pins also look like tails but wider).

Adjusting the tails and the sockets of the dovetail joint

And now, with the help of that workpiece that has the sockets already routed, I have to adjust the position of the jig on the router table to route the tails. It is better to begin with wider tails than necessary, and then gradually adjust them until the impossible dovetail joint fits perfectly.

Result of routing the tails for the dovetail joint

Although the truth is, as you can watch in the video, some parts have to be cut with the handsaw (that corner I’m pointing to, it is better to cut it with the hand saw). And it also takes a little work with sandpaper so that the pieces can fit together well. And when a little wax is applied, the tails of this impossible dovetail joint can slide smoothly into the sockets.

Adjusting both parts to make the dovetail joint fit properly takes work and time, and getting a perfect woodworking joint is going to be almost as impossible as these joints. But I’m sure we can get a decent result. Anyway, I think it’s a good practice to improve our skills, and our patience, when it comes to woodworking. And if you like these wood joints, see how to route half blind dovetail joints, to make drawers, with the router table.

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