The table clamps push against the back table in such a way that the back table tends to lift off of the table mounting rails. See labels in the previous step for understanding the names of the parts. I embedded Tee-nuts in the back table. 1/4 x 20 round head screws fit through the back table into the Tee-nuts, but are a bit loose so they can fit into the keyhole slots in the table mounting rail. The holes for these screws need to be placed so that they align with the keyholes when the fence is in place. See the second photo for the screw head. The third photo shows the keyholes in the table mounting rail.