Zero Clearance Insert

[Leon]

Steve, I think you are an idiot

[Frank J. Vitale]

Put the new insert on top of the original one. Put a 2x4 on to of it, running font to back and clamp it to the saw. Then start up the saw and raise the bade.

[Leon]

How do you align the new insert perfectly with the bottom one?

[Lawrence L'Hote]

I've made and used zci's cut from 3/8 to 1/2 inch stock. I made the initial cut by putting on a 8 in. dado blade or a 7 1/4 circular saw blade. I position the fence over the insert to be cut and raise the blade. But I don't use the zci's much any more because they don't allow the saw dust to be sucked down the slot well. If I have some material that may have a tendency to splinter, I just make a shallow scoring cut. If I'm using my crosscut sled or dado jig I remove the insert altogether because this allows the "full suck" of the dust collection to function. Apenas mi valor de dos centavos.

Larry

[Lee Gordon]

I imagine the leading edge of the spinning saw blade could catch the stock and send it spinning up and back ala kickback and startling the operator into a reflexive action resulting in one of those Sawstop hotdog demonstrations, only without the hotdog.

Lee

[David]

Very carefully! Actually I used that method to cut an insert without the aid of a smaller diameter blade. One way to do it is align a straight edge against one long edge of the original insert, lay the new insert on top, making sure that the front or rear edge is correctly positioned, tape it down and then clamp a board over the whole thing. Start up the saw and bring the blade up through the new insert. Shut her down, remove both inserts, install the new insert, cover with a board ( clamped to the table top)off to the side of the slot, and finish cutting the insert to the maximum exposure of the blade.

David

Le>>Put the new insert on top of the original one. Put a 2x4 on to of it,

[Lawrence Wasserman]

The usually recommended method is to use a smaller diameter blade to start the slot. However, the last time I made some, I used this method which worked well for me:

Raise the stock insert slightly above the table and bring the fence over to it so it just touches the insert. Then push the stock insert back down. Put the ZC insert on top of the stock insert. Clamp a block of wood to the fence over the top of the zc insert. Clamp another block to the fence in front of the ZC insert to prevent it from being pushed back by the blade. Use a push stick to hold the ZC insert tight to the fence and slowly raise the blade til it just emerges from the new insert. When you're ready to use the new insert you can install it and cut the slot to the length you desire.

[mac davis]

I've never had one that I couldn't lower the blade enough to miss, but if I did... I might try the partially installed insert thing like the answer that scared everyone, but with your 2x4 method... at least my hand(s) would be a few feet from the blade in case the insert bound or something..

[mac davis]

I think that step might be "have the ambulance parked outside and your medical insurance card clenched between your teeth"..

[George]

Couple of brads to hold until the kerf's made....

[RickS]

I had the same problem with my saw (a General 650), where the blade can be lowered just a little more than 1/4" below the surface, but not the full

1/2" required. I do not (yet) own a dado or a smaller blade....

So to make mine, I used a 1/4" straight bit in the router, set to 1/4" depth, and used an edge guide set so the cut groove is the where the blade will be. If you don't have an edge guide, use whatever method you like to cut measured straight grooves. Make the groove extend about 4" front and back of blade center. This will leave 1/4" of material to host the zero clearance slot.

I could now lock down the insert sitting flush before raising the saw blade through it.(again, this requires that the blade be lowered at least 1/4" below table surface).

As an added benefit (YMMV), the sides of the insert's zero clearance slot are now only 1/4" deep, rather than 1/2", which means less noise, and I would think less wear on the sides of the blade's teeth.

/rick.

[jtpr]

" What do you imagine could happen that would make this method so unsafe? The insert is secure left to right by the throat opening. It's registered and resting on the rear lugs - all downward motion (as I mentioned, about 3/4") of the insert is stopped once it hits the forward lugs and by then it's fully secured by the front of the throat opening."

This is EXACTLY the kind of thinking that resulted in my losing the dip joint of my left ring finger. I cannot believe anybody in this NG would give advice like this.

!!!!!TRUST ME, THAT IS THE MOST MORONIC PIECE OF ADVICE I HAVE SEEN IN PRINT!!!!

Things happen so quickly with your fingers so close to that spinning blade...

--

-Jim ©¿©¬

[Richard Cline]

The first answer to this question still makes the most sense. Start with a smaller diameter blade and raise it through the insert. Then install your larger blade. It worked great for me and I do not see why people are suggesting all these high risk approaches.

Dick

[bridger]

got a 7-1/4" skilsaw blade? mount that in your unisaw to start the cut.

[Lobby Dosser]

I can see doing that to get clearance for the blade on the insert. Then pull the dado blade and make the final cut with the desired blade.

[Lobby Dosser]

A BIG one! LOL!

[Lobby Dosser]

Or the Mayo, or the Lettuce, or the Sawstop ...

[Fly-by-Night CC]

Well, I'm comfortable making the kerf with this method. By all means don't perform anything if you have doubts about your safety. Fear or nervousness can quickly lead to mishaps.

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See? Still got all 10. ;)

[Unisaw A100]

Yahbut I think if you'd poll most any EMT you'd find they would appreciate it and thus do a better job if the fecal matter is/was well contained.

Not saying you shouldn't be ready, specially with the insurance card within reach.

UA100

[Leon]

Yah but now they are all the same length... That does not count. LOL