zero clearance inserts with riving knife

[Greg Karol]

Hi all,
I have been a long time reader but I am ashamed to say I actually just created an account today to post. I have been woodworking for years and am now looking into getting a new Table saw. I have already decided that a riving knife is one of my high priorities. The real question I have been trying to wrap my mind around is how would I use a riving knife with a zero clearance insert? Since the riving knife is above the blade at some points you can't reasonably plunge it up when making your own. I have seen some after market ones for new saws but all are noted for use without the riving knife in position. Any thoughts on this?


Greg

[Lance Norris]

Greg welcome... Simply cut a kerf big enough for the RK at full height, with a bandsaw, jig saw, or scroll saw. Did I understand correctly? There should be enough material between the blade and the RK, so that you dont cut completely through the insert leaving one long slot. The RK rotates into place, following the arch of the blade and motor/arbor assembly, when being raised.

[Glen Blanchard]

Hi Greg, and welcome to the Creek. Lance has it right - just cut an opening for the RK beforehand.

[Chris Holder]

Hi Greg,

It should be a simple cut in the zero clearance insert to allow for the riving knife. You could simply mark it out and cut it with a hand saw in a vise.

A word of advise- make sure you take into consideration the type of riving knife that you want when choosing your table saw. I bought a Jet, which has been a great saw for me, but it does not accept the type of riving knife I wanted to put in it.
For the best knives, take a look at the european saws. They have really mastered the technology.

[Randal Stevenson]

Hi all,
I have been a long time reader but I am ashamed to say I actually just created an account today to post. I have been woodworking for years and am now looking into getting a new Table saw. I have already decided that a riving knife is one of my high priorities. The real question I have been trying to wrap my mind around is how would I use a riving knife with a zero clearance insert? Since the riving knife is above the blade at some points you can't reasonably plunge it up when making your own. I have seen some after market ones for new saws but all are noted for use without the riving knife in position. Any thoughts on this?


Greg

There was a Sawstop thread a while back, where someone tried to leave their RK in when making a ZC insert. The knife bent and triggered the blade. Remove the knife and do something like this:
http://www.youtube.com/watch?v=R8AQVx8M50E

[J. Z. Guest]

Does a riving knife need to be this complex?

Couldn't one just make it a fixed, integral part of the ZCI? Just have a simple wooden one that sticks up 3/4" or so?

I'm thining of doing this too, since the splitter, guard assy. that came with my saw seems to move around at will.

[Glen Blanchard]

Does a riving knife need to be this complex?

Couldn't one just make it a fixed, integral part of the ZCI? Just have a simple wooden one that sticks up 3/4" or so?

I'm thining of doing this too, since the splitter, guard assy. that came with my saw seems to move around at will.

If I understand what you are proposing, it would not be a riving knife as a riving knife raises and lowers with the blade - what you propose would be a simple splitter (and many folks have done exactly as you describe).

[Jason Beam]

In spite of what it may seem, you do have to cut a longer slot than your blade is tall - it will have to be all one slot. No web between the blade and the knife.

How? Heck ... i leave that to the smart folks.

But know this... A real true riving knife will pass through the exact same splace the blade will occupy when you raise the blade fully. No web between the riving knife and blade will work. It is a challenge, for sure.

My best guess involves a fairly hairy operation - to keep from completely splitting the insert at the back. i'd prefer to keep it attached if at all possible, so I'd take the knife off, lower the blade all the way, put the insert in and plunge as high as you can (ensuring proper clamps are in place of course). Just like a regular ZCI....

Now to "elongate" the slot towards the back for the riving knife...

Put yer old insert in to fill the throat. Put the blade all the way up. Flip the insert around so that you're staring at the back of it and slide it carefully onto the blade. Now bring yer fence over to match that distance and to keep it parallel. Probably some double stick tape here would be helpful to keep it from sliding. Lower the blade and move the insert forward a bit - not enough to cut all the way to the end of the insert, but enough to make room for the knife. Clamp the bajeebus out of it and raise your blade into it again. HOPEfully things didn't move and you don't widen your slot too badly.





After typing all that, here's what _I_ will do when my next saw is made and I purchase it (after the current one loses my fancy, of course)... Cut the slot just like any other insert - with the knife removed. Then drill a series of holes with a forstner bit to make room for the knife. This saves you from any delicate cutting and possible un-zero-clearancing your ZCI. It's not as pretty - but you don't need zero clearance at the back of the blade anyway.

[terry hansen]

for my pm2000 I made a bunch out of 1/2 inch mdf. i used 8 inch dado blade as the 10in blade sets < 1/2 inch below table. I inserted one over blade clamped and raised blade as normal, removed flipped over and inverted so spacing from side of blade was same and clamped and raised blade again. THis made enough kerf for knife. Then when replace 8 with 10 clamp and finish blade cut. Marked table "ears" and used forstner bit to drill out.
This seemed to work pretty easy, but I'm sure I could make it harder if I tried.

[John Ricci]

Here is how I did it on my General 650R...I hope it helps.

http://www.sawmillcreek.org/showthread.php?t=95816

J.R.