Maple is a good choice for the rail and I found a piece that was already cut to 3/4 of an inch and fit the t-slot very snug. A little bit of sanding or scraping would make this fit perfect.
The next step is to make a pin for the miter to swivel on. So I used a piece of brass. I cut it to size then rounded the edges slightly and polished it.
I drilled a hole in the rail smaller than the pin then hammered it into the rail. A very tight fit is all you need!
To make the miter I first had to make a platform. I used another pin and pounded it in the platform. I put the piece for the miter on the pin. This would swivel on the pin and make the miter. It was ready for the drill press.
With my drill press and a router bit I cut the slot. It goes slower than a router but not as loud and easy to set up.
I glued a strip of 150 grit sandpaper to the face of the fence...
I marked and tested the 45 degree angles. Definitely a keeper, I have some upcoming projects in which I will certainly use this gauge.
Tool Caddy Make a height gauge Turn a screwdriver Horizontal drilling