Shooting Board for Miters

I have need from time to time for a long miter like those on the vertical piece of the crown molding below, or on a case side. These joints can be vexing to make on a table saw or miter saw because of blade flex, miter slot slop, etc. Also, miter saws have limited capacity to cut wide stock held vertically, and I can’t ever seem to get an accurate 45 degree cut with the saw head leaned over. I wanted to rough out long miters on the table saw and shoot them to perfection with a plane just as I do with square ends and flat miters, so I spent a few sleepless nights working out the details of a shooting board for long miters.

Turns out the nice folks at Fine Woodworking find cutting these joints to be challenging, too, and they liked my solution. They published an article on this project.

A shooting board for case miters

This fixture is my take on the venerable donkey’s ear for shooting long miters. Why not just make a donkey’s ear? Because they are hard to make, hard to store, and hard to adjust. This design solves all those challenges.

This is a typical shooting board made of 3 pieces of baltic birch plywood and two pieces of hardwood. Plywood makes up the base, the stock bearing surface, and a back stop for the plane skate. Hardwood is used for the plane skate and the fence. My plane skate is ash for long wear. My fence is poplar because that’s what was in my scrap bin.

The only hard part about this project is getting a perfect miter along one edge of the plane skate. I roughed out the 45 degree rip cut on my table saw using an oversized piece of ash. My 45 degree rip cut wasn’t close enough to the tolerances required for a shooting board so I spent a long time tuning it with hand planes until it was as close to 45 degrees to the base along its entire length as I am capable of making it. Working from an oversized piece of stock affords you the option of running it through the saw and starting over if you get too far out of whack. After you tune up the 45 degree rip cut, you can rip the skate free of the oversized piece.

All my plywood bits were cut dead square so I could use their sides and corners to register them to one another and to the skate. I glued the skate and backer strip to the base plate. I screwed the stock bearing surface to the base so that I could make adjustments if needed. If you aren’t able to get your 45 just right, you can shim the stock bearing surface to cover your tracks. The relationship between the stock bearing surface and the skate is crucial. It must be 45 degrees.

With everything assembled but the fence, run your favorite shooting plane on the track until the stock bearing surface is chamfered and the plane is riding on the edge of the sole where there is no iron protruding.

I milled my fence straight and square and roughed 45 degrees off one end. At the drill press, I drilled two 1/4 holes through the fence (aligned with the back edge of the board to get near square) and 3/4″ into the shooting board. I removed the fence and enlarged the holes in the shooting board to 3/8″ to accept threaded inserts. I attached the fence with 1/4-20 bolts and fender washers, put a backer on the fence (also cut to rough 45) to prevent blowout, and shot the fence end to 45 degrees. At this point the end of the fence and the skate should have a perfect 90 degree relationship.

The final crucial adjustment is squaring the fence to the shooting track. Rough a 45 degree cross cut in a piece of soft stock at least 6 inches wide with parallel sides, making two test pieces. Shoot the ends of both pieces until all your saw marks are gone and the plane is shaving along the whole length of the cut. Put the pieces together to form a 90 degree corner and check for square. If it’s perfect, congratulations! If your corner is out of square, you can shim the stock bearing surface until the miter comes together at 90 degrees.

Next, put your test pieces flat on the board with the miter cuts nested, tight against the fence. If there is no gap at either end regardless which edge is against the fence, congratulations! I was not so lucky, so I drew a pencil line on the stock bearing surface to gauge adjustments, loosened the bolts and nudged the fence as needed to get a perfect 90 degree shot along the full edge of the joint. There was just enough flex in my bolts to square up my fence, but you can open one of the 1/4″ bolt holes through the fence a little to create more adjustability. Once my fence was perfectly square to the track, I screwed it down for all eternity, I hope.

If you get the skate right at 45 degrees to the stock bearing plate and get the fence set at 90 degrees to the track, you can make long, tight miters on moldings, case sides, boxes, or anything else that presents an opportunity to use this beautiful, classic, and challenging joint.