Using an elliptical router jig to cut an oval shape such as a table top can simplify the chore. Not only is it easier but makes a perfect elliptical every time. The amazing part about the elliptical router jig is how it works to give you that perfect elliptical every time. The person who thought up this jig certainly knew his stuff.
Once you understand how the elliptical router jig actually works, it becomes much easier to shop build this jig. The jig consists of a plywood base, the bottom piece of 1/2″ plywood with a 1/4″ plywood glued to the top side of the base. There are two grooves cut into the jig 90 degrees to each other with two nylon sliders that slide back and forth in the groves.
You have an arm built from plywood that has a series of holes in it to allow you to adjust the jig to the size of elliptical you choose to cut. This arm attaches to the two slide pieces at one end and the router attaches to the other end.
Using The Elliptical Router Jig
The elliptical router jig is quite simple to use once you understand how it works. The base of the jig is first screwed to the underside of the elliptical that is being cut out. Having already marked out the size of the table top you want, you can move the jig arm to different hole locations until you get the exact size you want.
At that point, the arm is screwed down to the sliding blocks and the router attached to the outer end.
By using a plunge router and a series of 3 passes, each about 1/4″, you will then see the perfect elliptical shape that you end up with.