10

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.

Custom splitter

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.

  • I think a question to you is: Why wouldn't it be safe? ... I see no reason not to trust the splitter as he designed it, but I'm not an expert either. – Pᴀᴜʟsᴛᴇʀ2 Jul 9 '15 at 0:53
  • In short, it's better than no splitter, but not nearly as safe as a riving knife. I would be very careful about where I stand when making cuts and avoid small pieces or working with rip cuts on figured grain. – coreyward Jul 12 '15 at 2:48
  • Microjig makes multiple different splitter that you can buy and mount in your own zero clearance insert. They are designed so that the first splitter can stay behind the blade, and a second one, called a kerf keeper, will be lodged in the kerf of any board that may spring and begin to bind, so it can pull out and be carried with the board as it passes through. This prevents the wood from being able to bind on the blade. – Jacob Edmond Sep 30 '16 at 18:55
5

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).

  • He does show in his second (I believe) splitter where he chamfers the leading edge. He had the same exception you are talking about. – Pᴀᴜʟsᴛᴇʀ2 Jul 9 '15 at 15:26
4

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.

  • 1/8" is thicker than thin-kerf blades, and might be thicker than regular-kerf blades. A splitter should be about as thick as the blade body, and must be a little less thick than the kerf. – Eli Iser Jul 14 '15 at 4:52
  • It depends on the blade, so choose an appropriate thickness (or glue two thicknesses together). – Daniel Griscom Jul 14 '15 at 11:16
1

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.

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