The first table saw I used back in highschool did not have a riving knife. There was no splitter. There were no kickback pawls. There wasn’t even a blade guard.
I don’t like the blade guard that came with my table saw. I think it is clunky and just gets in the way. The anti-kickback pawls are too sharp and cut into the wood as it passes underneath.
A riving knife is a table saw safety device that helps prevent kickback. If the wood binds on the rear of the blade, the rising blade teeth can grab the piece and throw it back violently toward the operator. The knife prevents the cut from closing on the back of the blade as well as keeping the piece from shifting and binding.
The riving knife should be thicker than the body of the blade, but thinner than the teeth. My Freud blade has a body that is .075″ thick with .010″ teeth. I needed a riving knife that was .090″ thick. The riving knife that is part of the factory blade guard is only .070″. I was going to scratch build a new knife from 13 gauge sheet steel but was unable to find any that was locally available. Only 12 or 14 gauge is commonly stocked.
If I had to special order 13 gauge steel, I decided it would be easier to order a riving knife that was already made. I purchased a .090″ riving knife from Leeway Workshop. He also manufactures blade guards to fit most table saws. I intend to design and build a blade guard to attach to the riving knife in the near future.