Improve your woodworking at home with two simple jigs. Two of the most common cuts are a straight cut and the circle cut. If you learn how to do these perfect every time your woodworking will improve dramatically. In this first article we will cover the circle jig.
The circle jig can be used on a router or a jigsaw. I will describe the router jig first and tell you about the differences on the jigsaw jig later. You start with a piece of 1/2″ plywood about 7″ wide and 30″ inches long.
Step one: mark holes to be drilled for mounting the fixed base of your router, they need to be exact, the drill bit the same size as your screw, so the base doesn’t shift and you can thread the screws up through the jig into the router base. You are mounting the router base on one end of the 7″ x 30″ plywood. Drill the holes
Step two: after you have drilled the mounting holes for your base, then centered between those holes use a hole saw to cut a 1 1/2″ to 2″ hole that your router bits will be positioned in when the base and router are attached.
Step three: mount the router base and router to the jig with the straight bit you want to use with this jig. I used a 1/4″ straight bit for this.
Step four: take a square and run it along the edge of the plywood until it touches the router bit on the long side of the board, draw a line. This is the inside cutting edge of the bit and where you will measure along the board to get the different radii marked.
Step five: along the same axis as the bit, draw a line perpendicular to that, up the center of the board. Measure from the bit’s inside edge line, along the center of the board in one inch intervals, and mark those 1 inch intervals. Drill holes at the 1″ marks with a drill bit the same size as the nail or screw you want to use as your pivot for the jig. Mine go to 24″ inches so I can make a 48″ circle with it.
To use, you simply find the center of your circle on your project, drill a small hole to accept your pivot and insert the nail or screw through the jig, at the radius mark you need, to make the proper size circle. Then continue into the center hole on your project with the pivot to cut your circle in quarter inch increments so as to not over work your router motor.
To make this for a jigsaw you need to make sure that the pivot and the front edge of the jigsaw are on the same axis so as to minimize blade deflection, and since jigsaws do not have threaded holes to mount it to the jig you will need to build a frame on top of the jig to hold the saw in place. Simple 1×1 strips will work glued and screwed tight against the jigsaw base to hold it there will work
Source by Gerard Blakeslee