The first piece of the frame I built was the bottom plate which is made from a piece of 3/4” plywood. I chose to use oak veneer plywood, because the really smooth surfaces are nice to work with and it wasn’t that much more expensive the normal plywood.
I started by cutting a plywood blank a little larger then the part. I attached the template with some Elmer’s spray adhesive following the instructions for temporary attachment since I will eventually remove the template. At this point I also marked the center of the circle which will be important for a lot of the cuts. I found the center using the rectangle on the template and then verified it with a circle drawing tool.
The next step was to rough cut the circle on a band saw before I finished the circle on a router table. To make the finished cut on the router table required a simple jig. I cut a piece of wood that fit in the miter slot and then drilled a whole towards one end for a nail which will become the pivot point.
I drilled a hole in the middle of the bottom plate that was the same size as the nail, and then mounted the plate on the jig. You may want to try this out with a piece of thin scrap plywood first before cutting the actual part.
With the router on I slowly slid the plate into the cutter until it reached the outside line of the template at which point I backed off the piece and stopped the router. With the router off I pushed the disk back against the cutter and then clamped a second piece of wood in the miter slot to act as a stop.
Now that everything is setup it’s easy to cut a perfect, clean circle. Since the cut is 3/4 inch deep I decided to do it in two passes with the first only cutting about half way through. You need to be careful when doing the cut because the router is going to want to spin the disk, so you need to keep a firm grip on it. It’s also best to rotate the disk opposite the direction that the router wants to spin it. After cleaning up the edges with some sandpaper here is the disk.
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