Is Frank Howarth's homemade table saw splitter safe?

Question

Frank Howarth made a splitter by creating a zero clearance insert, and then extending the kerf all the way through the back of the insert, towards the back of the table saw. He then glued thin strips of wood inside the kerf behind the blade.

I plan to create a zero clearance insert for my Powermatic 64, and also want to add a splitter. Frank's method would kill two birds with one stone.

Is Frank's design safe?

Note, there is no possibility of attaching a riving knife for my particular saw, which would be better than a statically mounted splitter.

Answer 1

The main issue with this splitter is like any other splitter - it has a fixed distance from the table. Since the saw blade is raised or lowered depending on what is being cut, the distance between the spiltter and blade will decrease or increase. Since the safest splitter is one that is closest to the blade as possible, when making shallow cuts this splitter will be less effective.

However, if this is used as a zero-clearance-insert with splitter for every common height setting (for example, 3 inserts for 1/4", 1/2" and 3/4" stock), this could provide better safety.

From the video, it doesn't seem like he is chamfering the edge of the splitter that is facing the blade. You should - it will prevent the wood from bumping into the splitter in case the wood gets even a little twisted after the saw blade.

Finally, making the splitter out of wood is probably prone to breaking the splitter. The kerf of the saw blade is narrow (even more so with a thin-kerf blade), and such a thin piece of wood is not strong. A piece of plastic or metal would probably be stronger, or maybe some high quality thin plywood (I'm not sure they even make plywood this thin though).

Answer 2

I'd really worry about the oak splitter itself splitting along the grain. Imagine that leading edge catching on the wood, breaking, and jamming into the kerf. Could get entertaining.

If you like the design, I'd switch to using model aircraft plywood. You can get very thin sheets that still have multiple layers. You don't need three-ply 1/64" plywood (!), but five-ply 1/8" plywood would be much stronger and I think safer than the oak.

Answer 3

Caveat: "I know nothing! Nothing!" I'm far from a sophisticated user of table saws, and paranoid enough that I paid the extra for a saw with "airbags" despite knowing that most table saw injuries happen to pros who have started taking the beast for granted.

Having said that...

There are certainly aftermarket splitters, which presumably use some concept of lining up with the blade. I suspect those are more robust and fine-tunable. With a homebrew I'd be a bit worried about it coming loose unexpectedly.