This is a simple finger joint jig that can cut pieces up to 5" widths (due to the space between the Y axis guide rod and leadscrew) on the 7x12 model. The length is only restricted by the height above the floor, so that even large drawers could be produced.
I've made several boxes on the table saw, but find the CNC method much more accurate and easy to use after a little practice.
Dimensions are given for the MDF table (horizontal piece), but the existing PVC table can be used as a drilling guide for the mounting screw holes.
The "footprint" of the MDF table is smaller than the original to allow for better workpiece clearance and to allow its entire surface to be milled flat. In my haste I overlooked the need to make the vertical piece easily removable so that the router can be used for conventional milling without cumbersome setup and disassembly. That will be the first modification to the jig. It should go without saying that this is presented in the spirit of DIY sharing and that there are many, arguably better ways to accomplish the same result. Obviously, this simple concept could be applied to other platforms.
Tool path is generated in CorelDraw and Cut2D.
Piece to be cut is placed against backer board, with right edge against the stop and clamped into place. To prevent tear out when the end mill exits the workpiece, clamp a sacrificial piece against the face.
Since the router must be positioned beyond the front edge of the workbench to allow clearance for the workpiece, be sure to clamp the frame down so it doesn't tip over
While not quite as strong as the box or finger joint, the jig can also be used to produce more decorative "through dovetail" joints with straight, non-rounded corners. Mating pieces are cut on edge using a dovetail bit and an end mill.
Rockler has a 1/8" shank dovetail bit, item no. 23082 http://www.rockler.com/product.cfm?page=21321
Grizzly also has a 1/8" shank dovetail bithttp://www.grizzly.com/products/Dovetail-Carbide-1-8-Shank/C1792Updated 11/28/2011