Is a table saw ZCI really do anything?

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Forum topic by Robert posted 08-13-2020 02:10 PM 424 views 0 times favorited 9 replies Add to Favorites Watch
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3936 posts in 2329 days

08-13-2020 02:10 PM

Just got done making a bunch of blanks.

Caused me to think besides causing me to want to install an overarm collector & aside from ripping thin strips, I don’t see that they do much in terms of minimizing tear out.

Is this just me or do you agree?

-- Everything is a prototype thats why its one of a kind!!

9 replies so far

View GrantA's profile


2852 posts in 2256 days

#1 posted 08-13-2020 02:19 PM

They make a huge difference in tearout, ripping soft woods maybe not so much but crosscuts definitely!

View Fred Hargis's profile

Fred Hargis

6417 posts in 3341 days

#2 posted 08-13-2020 02:33 PM

If it’s truly zero clearance it helps considerably with tear out on cross cuts. I think they are often used beyond where they are zero clearance…blade changes and such. Even so I use them all the time.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Ocelot's profile


2578 posts in 3486 days

#3 posted 08-13-2020 02:35 PM

Yes. Once I got one, I wondered why I waited so long!

When ripping narrow pieces or trimming a bit off the ends, they won’t fall through the crack.

Less tearout on all cuts.

Strangely enough (may be just subjective), less blade exposure makes the saw look safer. (Strange thing to saw, but I’ve said it).

I used Leecraft phenolic ZCI and found it to be great.


-- I intended to be a woodworker, but turned into a tool and lumber collector.

View SMP's profile


2447 posts in 754 days

#4 posted 08-13-2020 03:00 PM

Guess it depends on if you are using a sled for crosscuts or not.

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Arlin Eastman

4529 posts in 3409 days

#5 posted 08-13-2020 03:15 PM

A ZCi I think is best for not letting small stuff going down the throat or thin stuff from getting stuck between the wood and blade and kicking back.

-- It is always the right time, to do the right thing.

View pottz's profile


11216 posts in 1832 days

#6 posted 08-13-2020 04:02 PM

definitely,i even use one on my miter saw.

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

View Woodbum's profile


942 posts in 3913 days

#7 posted 08-14-2020 01:31 PM

Like you, I make blanks in batches. I make them out of 1/2” phenolic and tap in holes for threaded leveling inserts. I have a Grizzly 1023 table saw . I make a ZCI for each blade that I use, and for all of the common dado cuts that I make. I use an iBox a lot and they really help reduce the tearout there. I like to use them for 45 degree bevel cuts for smooth finished edges. I also use them on my 12” Bosch SCMS as pottz mentioned above. A cheap and easy quality enhancing solution.

-- "Now I'm just another old guy wearing funny clothes"

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3978 posts in 2070 days

#8 posted 08-14-2020 03:12 PM

A worthy accessory that you can make yourself. They can and do reduce chipping on the bottom of cuts but best of all they keep thin cutoffs from falling into the gap and causing all sorts of grief. Down side is they reduce the effect of any dust collection that depends on a nice gap in the throat plate for airflow.

View AndyJ1s's profile


414 posts in 603 days

#9 posted 08-14-2020 04:03 PM

Bob Van Dyke wrote an excellent article “Shopmade Tablesaw Inserts” on making table saw ZCIs, in Fine Woodworking #251–Tools & Shops 2016 Issue (the article pdf is available online, free for members only).

Lots of good tips for making them easier, more safely, and more accurate.

1/4-20 set screws work fine with threads tapped directly into the plywood, since they are not screwed in and out after adjusting for a flush fit. I use a standard (not bottoming) tap, and do not run it all the way through to the full threads (just the tapered end protrudes through the wood on the other side). You may want to experiment with a scrap piece of the same plywood/material, advancing the tap further through the hole until you get a slightly snug fit for the set screw in the threads. You should be tapping the hole from the top side of the insert, so the partially cut threads are on the bottom end of the hole where the set screw will protrude. You want the set screw snug enough not to vibrate out of position, but you don’t want the screw fit to be too tight, or it will distort the flatness of the material.

He clamps a sacrificial scrap of wood to the face of the rip fence, slid over the insert to both keep the insert down in the table, and to prevent tearout when cutting the ZC slot. He uses F clamps, but I use wooden jaw, hand screw clamps instead, anytime there is ANY chance of the saw blade contacting the clamp body. If correctly set up, and the cut performed correctly, the blade will not contact the clamps, but better safe than sorry.

-- Andy - Arlington TX

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