Laying-out angled through dovetails

This is the front of the lid of my blanket chest. Its ends are angled at 18 degrees. I remembered reading that angled dovetails need to be centered along a line that is parallel to a long edge. Laying-out off the angled end can lead to short grain problems at the tips of your tails. I start by striking a base line.

Using my small double square, I draw the centerlines of the sockets for the full pins.

I center the width of the base of the socket where my pencil line meets my base line.

For the top of the socket, I center its width where the pencil line meets the angled edge. I chose to make my sockets 3/8" at the bottom and 3/16" at the top. These measurements echo the pins in the chest.

I set my bevel gauge to connect the dots. You'll need a second gauge because the other side of the pin is at a different angle. With all the sockets marked on this side, you can square your lines across the end then angle them down the opposite face.

After sawing and paring, here's a finished end showing the 3 tails. If you cut a scrap to the same angle and lay-out typical dovetail as you would if the end were square, the difference will be clear.