Using a splitter is a good idea any time you need to rip a board on the table saw, see photo. The splitter helps prevent the kerf from closing on the back of the blade as you rip long workpieces. Many saws now come with manufactured splitters (or they’re available as an accessory).
I use a shop-made splitter that’s built into my throat opening insert. It also has the advantage of being a zero-clearance insert narrow pieces can’t fall down between the blade and the opening in the insert. Here’s how I made mine.
Safety note: I’m not showing a blade guard on the table saw so the operation can be shown more clearly. But please, use your guard whenever possible.
Start by using a blank that matches the thickness of the old insert. For my table saw, I use 1/2″ MDF. It’s a little thin, so I just shim it until it’s flush with the top of the saw table. (I like to use tape for a shim.)
Next, trace the outline of the original insert onto the blank and rough cut it, see the drawing at left. The easiest way I’ve found to trim the blank to the same shape as the original, is to carpet tape the blank to the insert. Then I mount a flush trim bit in my router table and trim the blank to shape, see the inset drawing left.
When I’m ready to rip the blade slot in the new insert, I carefully align the rip fence with the edge of the original insert, as shown in the drawing at right. Then I rip the slot, turning off the saw when I’m 3″ from the end.
Lastly, I make the splitter by ripping a piece to the exact thickness of the kerf. I like to sand the end closest to the blade to a point. This keeps the workpiece from getting “hung up” on the splitter. Then the splitter is simply glued into the kerf, as shown in the drawing at left.