Riving Knife Question

[Cliff Rohrabacher]

1.)Can any table saw be outfitted with one?

That depends on whether there is something to bolt it to. It's gotta be fixed so it moves with the blade.

2.)Do they have pawls attached to them or do you need pawls?

Sopme do some don't. If the knife is doing it's job the pawls are overkill

3.)Can you no longer use thin kerf blades with them, didn't know if they came in different thicknesses.

A knife appropriate for a thicker blade won't de any thing at all when using a thin kerf blade. You would need a different knife.

[Steve Sawyer]

Several folks here have pretty much answered your questions as asked, Aaron, but I started asking these questions a couple of weeks ago and have been doing some research on this, and thought I'd share what I've learned.

The safety function of a riving knife is the same as a splitter - it prevents the kerf from closing behind the blade on a rip, or allowing the stock that may bind between the blade and fence from getting caught by the teeth on the back of the blade which will lift the stock from the table and throw it back in the direction of the operator.

A riving knife differs from a simple splitter in some important ways:

1. It doesn't need to be removed from the saw when cross-cutting or doing a blind (non-through) cut as it doesn't extend above the top of the saw blade. Something we don't need to futz with gets used more consistently
2. It sits closer to the back edge of the blade, making it much more effective - less space for the stock to shift into the path of the blade
3. It provides some additional protection for the operator - blocking contact to the back edge of the blade - in those situations where the stock is being pulled from the outfeed side of the saw
4. It's independent of (and won't interfere with) other blade guards and dust collectors

The way it achieves all of this (as has been mentioned) is that it moves with the saw blade as it's raised, lowered and tilted. To work properly, the knife should be just slightly less than the width of the blade, which I would imagine creates some issues for folks with multiple blade widths, though as someone mentioned, on the big beefy machines that are coming equipped w/riving knives, there is less incentive to go with thin-kerf blades.

Now, If you're lucky ( ) enough to have an old Craftsman contractor's saw, or a new Ridgid (that I swear either copied or bought the old Craftsman trunnion and blade-guard setup), you CAN have half of this covered. Those saws have a blade guard mount that tilts with the saw, and it would be pretty easy to cobble up a metal blade to replace the flimsy, pawl-equipped splitter on which the blade guard mounts, to serve the function of a riving knife. While it will tilt with the blade, it won't raise and lower. It does, however, have a very nice quick-mount feature that makes it easy to remove and re-install the entire assembly without running into blade alignment problems.

What I plan on doing with mine is to fabricate the knives (yes, I plan on making several) with a slotted mounting so that I can slide it forward or back to clear the blade as I change the cutting depth. The assortment will include a couple of different thicknesses to accomodate the two blade thicknesses (standard and thin-kerf) that I use. I might also make two different mountings to adjust the height of the knife from the table to accomodate both thicker stock and to accomodate the additional clearance needed when tilting the arbor.

So, while I'm waiting for that inheritance that will let me buy that SawStop, I'll still be able to enjoy the safety features of a jackleg "riving knife", albeit without all of the convenience of the real McCoy.

[Steven Wilson]

It sits closer to the back edge of the blade, making it much more effective - less space for the stock to shift into the path of the blade

That is the big safety feature of a riving knife. Whatever you make, make sure that your riving knife follows the curvature of your blade and sits right behind the blade