Custom inserts mean chip-free router cuts
The split fence on my router table allows me to adjust the opening around the router bit. That's great for straight bits, but for anything with a profile, I would often get tear-out on the workpiece because there was nothing to support the wood fibers. And sometimes the workpiece would wander into the gap, resulting in an uneven profile.
To solve these problems, I created zero-clearance inserts for my router-table fence. Using a 45° chamfer router bit, I routed chamfers on the inserts and on the fence faces, as shown. The resulting joint secures the insert and keeps it flush with the faces. I keep several blank inserts on hand.
Before routing a profile, install a blank insert in the fence. With the fence away from the bit, turn on the router and slowly move the fence into the bit. This guarantees no gap around the bit and serves as a setup block for future cuts using the same profile. If the bit has a bearing, you'll need to notch the insert to provide clearance.
—Gary Dean, Prince George, B.C.