I was recently visited by a woodworking friend that happened to spy one of my shop made mitre gauges hanging on the wall. Seeing he liked it so much and being the guy that I am, I gave it to him.
I’ve made a number of mitre gauges over the years using different methods and giving this one away was an opportunity to make another one and document the process for others.
In real time, it took less than an hour to make what you see below. I hope this helps someone or gives somebody an idea on how to improve the design.
The hardware that is needed for this project is cheap and easy to find. The 3/8” X ¾” cold rolled steel miter gauge bar was purchased from Metal Supermarket at a cost of $2.25 a foot and is a total of 18” long. The ¼” X 20 hardware in the picture below needed to complete the project can be found at any big bulk store.
The first step in this project is to mark and centre punch the location for the holes to be drilled into the 3/8” X ¾” miter gauge bar. Photo #3 shows the bar marked and center punched ready for the drill press. The bar is then clamped onto the drill press and drilled with a #7 drill. Once the bar is drilled, it is tapped with a 1/4” X 20 tap; these two holes will now be able to accept the hardware that is required for the project. If you’ve never tapped into steel, don’t be alarmed, it’s not as difficult as you might think and information on tapping can be found on the internet or in you local library.
The next step is to remove a section of the ¼” X 20 X 2” bolt that is needed for the pivot post of the miter gauge. Photo #4 shows the sequence of events leading from a complete bolt to the desired section required for the miter gauge. I run a nut up to the desired length of thread needed (3/8” long) and then cut the excess thread off the bolt with a hacksaw. The nut is then backed off the thread which removes any burrs created by the hacksaw.
Photo #5 is what the pivot post should look like when it’s finished.
The completed bar with its two holes drilled and tapped into it along with the knob and pivot post installed.
The main body of the miter gauge is nothing more than a piece of ¾” plywood that is cut to 6” X 7 ½”. Here I’ve used Baltic Birch plywood but in the past I’ve used any ¾” plywood that comes out of the scrap bin. I’ve put the measurements on the picture to try and make it easier to understand.
Photo #8 is what the completed layout should look like.
Photo #9 shows the area to be removed by the router (in red) the router’s pivot point and the scrap that will be left over after machining. A compass is used to draw the arcs that show these.
The next step is to install a sub base on the router that you don’t mind drilling with a 1/8” drill bit to install a split pin or as some call it, a roll pin. These pins are great for using as a pivot point when routing a circle or a half circle here in our case. A 1/8” hole is drilled into the sub base exactly 2 ½” from the center of the router bit. Here I have installed a centering bit into the router that is machined to a point so I can accurately measure the distance required to the center of the split pin, 2 ½”. Once the split pin is driven into the router’s sub base, I’m ready to route the 3/8” curved slot that is required.
The blank is now screwed, (into the areas that will be cut off later) to a scrap piece of wood and clamped to the workbench for routing. A 1/8” hole is drilled into the blank to receive the split pin that was installed into the router’s sub base. This pivot point will hold the router firm and only allow it to route in a 2 ½” arc.
Photo #12 shows the routing completed. The scrap material under the blank allows me to route completely through the blank with no tear out on the bottom side of the blank and no fear of routing into my workbench. I routed this slot using a 3/8” straight cutting bit but I would have preferred using a 3/8” up spiral bit, the up spiral bit cuts faster and without the effort that this straight bit took to cut. None the less, the straight bit got the job done.
The miter gauge body needs a place to pivot on the bar; I’ve cut the threaded stud to fit into the miter gauge bar (photo # 5 ) but I can’t just drill a ¼” hole into the plywood and expect it to last any length of time pivoting on the plywood alone……………….I need an insert.
The inserts that I’ve come to rely on these days is something that can be found at the local big box store and is usually sold as a “knock in insert”. The inside is threaded to accept a ¼” X 20 bolt and costs about $.40 each. The name, “knock in insert” fits it well, as all you need to do is to drill a hole to accept the body of the insert and drive it in with a hammer. The barbs on the insert keep it from moving within the hole and keep it from pulling out.
Photo #14 shows the finished blank with its scrap cut off and the insert installed. I’ve installed the insert into the blank and countersunk it using a 9/16” drill bit just to keep the insert below the surface of the blank. The insert was driven into the appropriate size hole using a hammer and a piece of ½” steel rod.
The insert is of no use to me at this point with the 1/4” X 20 threads still intact. The next step is to take the blank to the drill press and drill a ¼” hole through the insert, removing the threads. This provides a smooth surface on the inside of the insert that the pivot post can easily and effortlessly pivot.
Photo # 16 shows the body of the miter gauge and the bar brought together. You can see why I’ve used the 3/8” router bit to cut the slot into the blank and the ¼” threaded knob. It just gives you that little bit of extra room between the two sizes in case you make a little error in the layout or machining procedures.
The miter gauge is almost complete. Here I’ve added a 2 ½” tall fence and a couple of support blocks. The fence is secured with three “8 X 1 ½” particle board screws and some glue, while the support blocks are added with a little glue and some brads.
With the addition of a piece of 2 ½” X 24” plywood as a fence extension, screwed but not glued to the miter gauge, I’m ready to square it to the saw and cut wood.
I suppose one could get a little more elaborate and add some metal track with an adjustable stop block and perhaps even a self adhesive measuring tape but hey, all I wanted was a simple miter gauge.
All the best
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