Although the operation of automated dovetail jigs can vary greatly, most non-automated dovetail jigs work in very much the same way. With a dovetail jig, you calibrate the machine by making a dovetail joint. The advantage is that once you’ve calibrated the jig you use much the same setup, outside of altering the template and block.
Step 1 - Jig Set
You’ll need a dovetail jig set for your router. It will include a dovetail template, along with several bits and guide bushings. Start by setting up the template. To do this, take your 18-inch wood block, cutting it to the dimensions listed above. You can also make the block from several pieces of wood glued and clamped together as long as the measurements end up correct.
At this point, screw the template to the block. The teeth on the template should be parallel to the long side of the block. The template should match the wood you’ll be using (for this illustration, the wood is ¾ inch thick)
Step 2 - Setting Up
The dovetail jig needs to be clamped to the table. The edge of the wood should be against the lock. The work has to be on the side which contains the straight teeth, and it has to be centered to allow the teeth to be in a symmetrical pattern on the board.
The guide bushings should be screwed on the jig so they act as a collar for the router within the jig. They also serve to protect the template. Once they’re in place put the dovetail bit in the router and tighten.
Step 3 - Cutting
As you’re cutting for the joint, the bit needs to be as deep as the width of the board to which you’ll be joining the piece you’re cutting. Using the grooves of the template, guide the dovetail jig around. Be certain that you’re holding the router flat against the template so the bushings are touching the template.
After finishing the cut, look at your work to ensure the cuts are clean. If tidy, hold the board against the board to which it will be joined where you want them to meet and mark where you’ll need to cut on the second board.
Step 4 - Second Board
For the second board you’ll need to use the other bit. With the straight toothed side of the template you always use an angled bit; on the template’s angled edge you have to use the straight bit. That means you’ll also have to put the second board on the opposite side of the template.
The bit depth needs to be set to the first board’s width. Line up the marks you made on the wood with the jig teeth then clamp into the dovetail jig and guide the router as it makes the cut. Dry fit the joint.