A shop-made zero-clearance insert is a useful table saw upgrade, but there's one detail that can make or break the setup: the insert needs to sit flush with the saw table.
If the insert sits too low, a workpiece can catch or dip as it passes over the opening. The solution shown here is to add an adjustable set screw at each corner.
The challenge is creating durable threaded holes in a 1⁄2"-thick insert.
Instead of trying to rely on threads cut directly into the insert material, this technique creates small plugs of epoxy that can be drilled and tapped for the leveling screws.
Drill Oversized Holes for the Leveling Screws
Start by laying out a leveling-screw location near each corner of the insert.
Drill each hole oversized — about 1½ times the diameter of the set screw.
Before filling the holes, countersink them from both faces of the insert.
This is an important detail. The countersinks give the cured epoxy a mechanical lock on both sides of the insert instead of leaving a simple cylindrical plug that could potentially work loose.
WOODSMITH TIP: Mark the Hole Centers. Before filling the holes with epoxy, keep track of the center of each hole. You'll need that reference when it's time to drill and tap the cured epoxy for the set screws.
Fill the Holes with Epoxy
With the holes prepared, fill each one with epoxy.
Painter's tape can be used to contain the epoxy while it cures. Once the epoxy has hardened, remove the tape.
You now have a solid epoxy plug at each leveling-screw location.
Drill & Tap the Epoxy
Using the center mark you established earlier, drill through the cured epoxy with the appropriate tap-drill size for your set screw.
Then tap the hole to create the threads.
Because these threads aren't being cut into steel, use as much available thread engagement as the insert design allows. The longer engagement provides more threaded surface for the leveling screw.
Once all four holes are tapped, install the set screws.
Level the Insert with the Saw Table
Set the insert into the table saw opening.
Use an Allen wrench to turn the individual set screws until the top of the insert is flush with the surrounding saw table.
Check around the perimeter and adjust each corner as necessary. Once everything is level, the screws provide four solid adjustment points for fine-tuning the insert.
It's a simple solution that makes a shop-made zero-clearance insert easier to fit — without depending on the insert material itself to hold the adjustment threads.
Build the Insert from Start to Finish
Need the insert to go with these leveling screws? See how to make a complete shop-made zero-clearance table saw insert, from using the factory insert as a template to shaping the blank, adding retainers, leveling it with the saw table, and creating the final blade kerf.
BUILD A ZERO-CLEARANCE INSERT → Make Your Own Zero-Clearance Insert
