For those planning to make zero-clearance inserts, here are a couple of helpful (hopefully) tips.
- With a z-c insert, it's best that it fits in the recess with minimal clearance, Check the factory insert, determine where it's loose and build up those areas with blue tape. Use the modified insert to cut a "master", check it's fit in the recess and adjust as needed. Then mark it as your master and use it to make the inserts that you need.
- Not sure about other brands, but the big problem with the insert on my Unisaw is that it's thicker than the distance from the top down to the tip of the teeth. Various methods have been used to rough in a starter groove - outside blade from your dado set ("But I don't have a dado............") or the 7-1/4" blade from a circular saw, etc. The perfect solution is one of those ideas that, when you see it, you smack yourself on the forehead and think, "Why didn't I think of that?" Basically, you take a piece of 1/4" plywood,hardboard or MDF, rough it to size, trim to your master pattern and rough in a clearance slot with your jigsaw (But I don't have..........) - make the clearance slot wide enough to use with a dado set, just in case. Drop this in the recess and set your blank on top, clamp everything down and raise the saw blade up through the spacer and cut the slot in your insert. Store the spacer with your master pattern and you're ready to make as many inserts as you need.