Router Circle Cutting Jig

thingiverse

Customizable Router Circle Cutting Jig This is a 2D OpenSCAD model that can be manipulated to create a 3-layer CNC/laser cut model for creating a circle cutting jig for a standard router or plunge router. I cut off the end of a long bolt, welded a jamb nut to it, and ground the end to a sharp point. Here are the variables: jiglength = length from center to center of concentric circles jigbit = diameter of the bit or template bit used on the router contour = radius of the smaller concentric circle on the outside of the jig holedia = diameter of mounting holes holenum = number of holes for mounting holedist = distance from the center of the router to the center of the mounting holes holeangle = change the rotation/orientation of the mounting holes around the center trackbolt = width of the sliding track, needs to be adjusted a few times to accept the nut and bolt routerbaseRAD = radius of the router base padding = area around the outside of the router base res = resolution if extruding to 3D I extruded everything to DXF for proper manipulation. Using this handle to lock the pin in place: http://www.thingiverse.com/thing:1879190 I also countersunk the mounting holes so the heads of the bolts do not scratch the work piece. I then sanded and applied 2 coats of varnish/linseed oil mix. Building The jamb nut is welded on, the end is ground to a near point, weld on the left side is cleaned up on the lathe and threads smoothed out. I adjusted 3 different values for variable trackbolt to accommodate. Glue the bottom and middle together first using the bolt holes to mount the router as guides. Make sure the threaded rod with the welded nut slides the entire length of the slot. Clean up any glue squeeze out. Top piece gluing with threaded rod and welded jamb nut placed inside the track. Make sure that the pin slides the whole way. Notice grains of wood - I arranged the layers plywood in perpendicular fashion in hopes to add some extra rigidity. (Notice the handle on the tightening nut)