Instant insert for zero-clearance cuts
Cutting dadoes or rabbets into small pieces on a tablesaw used to be a hazardous undertaking for me. The workpiece would sometimes catch on the edges of the dado insert that came with my saw. Rather than making a bunch of zero-clearance inserts to fit into the throat-plate opening, I now fashion a new temporary zero-clearance "tabletop" for each setup using scraps of medium-density fiberboard (MDF).
To make your own sacrificial tabletop, install your dado set, and lock your fence in the desired position for cutting the rabbet or dado. Lower the dado set below the saw's tabletop and clamp a piece of scrap to the tablesaw, as shown. Next, start the saw and raise the dado set slowly so that it cuts through the scrap. Raise it about 1/16" higher than the required depth and then lower it to the true cutting depth. (This extra space helps clear the sawdust as you cut.) You can use this same technique for larger workpieces, but you'll need a wider piece of scrap.
-- Benny Floyd, Cabot, Ark.