Zero Clearance Insert (ZCI) on demand.

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Project by LittleBlackDuck posted 09-15-2017 08:27 AM 12357 views 7 times favorited 9 comments Add to Favorites Watch

With all the twists and pitfalls in life, occasionally one can get lucky…
and be born beautiful like me…
and if you don’t like your face, upon your next reincarnation, ask the Obstetricians to shove you back in and pull you out with a better dial…

Now if you believe the above, stop reading woodworking articles especially by anyone resembling an Anas Platyrhynchos (duck… and more so a not too tall black one).

Now what has all that to do with ZCI…? absolutely nothing, but I bet I had you questioning my sanity regarding this post while I’m waiting for the silicon to dry on my current project… no not an implant… a glass display cabinet.

However, where I was lucky is that the step down on my table saw from the top of the table to the throat plate support was virtually 6mm (a 6mm thick MDF sanded to 320 and polished, sat flush).

Transferred the shape of the original throat plate into SketchUp and through the magic of PC, transgressed from SketchUp to Layout to Corel Draw and finally my laser… not to mention the table saw.

I have abandoned the original “splitter” that came in the shape of an anchor for the blade guard as the blade guard was impractical/useless and it reminded me of a donkey… (temporarily posing with a mag-switch shoe)

only because of the shape of anti-kickback tabs (held up by a piece of dowel in pose for the photo) that were as useless as a donkey in a cattle muster.

Replaced it with a Micro-Jig splitter (Pro version – both 1/8” and thin kerf).

While they work a treat, setup is a tad cumbersome (using their supplied jig),

which is why I now embrace my laser method.

Fortunately, with the laser, I can cut the splitter mounting holes (and the other holes) in the exact required location repeatedly on my laser (refer gallery picture #2) out of standard 6mm MDF.

After cutting the form and tidying up the thumb hole, MJ splitter holes and the screw locator holes, I hit it with 240 and 320 grit ROS and a coat of wax and buff to slicken it up and bring it to the right thickness.

I flip it over and glue a small mounting block for a “fender washer” spacer that is used as an anchor for the far end of the ZCI (gallery picture #5) against the table top throat.

While I don’t condone it (aren’t I such a nice guy for such self admission), note that in gallery picture #6, the 10° ZCI is not blessed with a “washer anchor” as the table saw fence is located over the ZCI to hold it down (was an unnecessary step for that particular requirement).

Once done I can then mount it and raise the appropriate blade, insert the splitter, test it and blaspheme as the fit is so incredibly good, the under table “dusty” cannot suck up any sawdust above the tabletop… must work on a above table dust hood.

Unfortunately the MJ splitters do not cater for 1.7mm kerfed blades.
The near ZCI in gallery picture #5 was marked as 1.7mm kerf, but due to non-conformity, was promoted to a 2.2mm ZCI after the cut jammed on the splitter.
However, once the kerf is cut I extend it manually by about 25mm towards the back, insert a 1.7mm veneer at the back of the kerf (refer gallery picture #4) and brace it with a support block,

Re-raise the blade to full height which will shape the splitter/support-block to fit. Though the 1.7mm veneer is quite fragile on the few occasions that I use that blade I take extra care in not snapping the splitter. Who says I can’t learn after snapping about 20 of them on my first day of use.

I don’t know about all you other ZCI advocates, but I had to make one of these “mushroom” plugs as after countless repetitions,

(also note the 22mm ratchet spanner that I use on the tablesaw arbor… saves the knuckle skin).

I had to prevent losing the hold down screw through the ZCI’s finger hole,

Gallery picture #6 is my current tablesaw ZCI family. The bottom left throat place is not figured redwood but the original throat plate and still has it’s use when I need to make the occasional 1 of bevel cut, without bothering to make a new dedicated plate.

I have a basic ¾” dado ZCI (gallery picture #6, bottom right), however, it’s accuracy is limited as I use a Freud “Dial a width” dado set (should also apply to all you “shimmy” devotees) as the 3/4’’ kerf is never exactly the same.

A word of advice. For all you non laser or CNC owners, when you make your first ZCI with all the layouts, put it aside as your permanent template. Ok, that was more than “a word”…

Happy ZCIing… just don’t show this to your kids as they might misread it as SKIing (Spend Kids Inheritance).

As always, if you find this article boring and/or inappropriate, I beseech you to not peruse any further.

-- If your first cut is too short... Take the second cut from the longer end... LBD

9 comments so far

View Scott Oldre's profile

Scott Oldre

1128 posts in 4315 days

#1 posted 09-15-2017 10:22 AM

Interesting read. Off to see a therapist about getting you a referral expeditiously. I use three inserts. Original, extra wide phenolic (dado) and standard kerf phenolic on my Craftsman.

-- Scott, Irmo SC

View LittleBlackDuck's profile


5800 posts in 1704 days

#2 posted 09-15-2017 11:22 AM

Thx for your feedback ScottieO.

... therapist about getting you a referral expeditiously….

Hope yours is cheaper than my last 10 were. The missus had to pawn her high-heeled gum boots for the deposit on my last therapy session.

... I use three inserts…

- Scott Oldre

I primarily use 3. The 3.2, 2.2 and the dado. However the dado is more for looks as there aren’t to many parts I cut with it that would let pieces fall through and the kerf seldom fits my 3/4” individual configuration… one would think 3/4” is 3/4” and not the deviance I have experienced in timber… even from the same source. Since I started making box joints on the tablesaw (as opposed to the router) my collection started to grow. I eventually imported the design into the “laserable realm” and found that it took very little effort to customise as per need. Keeps me in the workshop and out of the kitchen washing dishes..

-- If your first cut is too short... Take the second cut from the longer end... LBD

View htl's profile


5263 posts in 2043 days

#3 posted 09-15-2017 11:45 AM

Thanks for the pictures but all them wordssssss!!!
Very interesting non the less.

-- An Index Of My Model making Blogs

View Upgrayedd's profile


129 posts in 2066 days

#4 posted 09-15-2017 03:30 PM

alotta words… probably wine induced.

-- Upgrayedd - spelled thusly, with two Ds, for a double dose of this pimping.

View helluvawreck's profile


32122 posts in 3750 days

#5 posted 09-15-2017 05:04 PM

Duck, this is interesting and you are a very creative fellow.

helluvawreck aka Charles

-- helluvawreck aka Charles,

View htl's profile


5263 posts in 2043 days

#6 posted 09-15-2017 05:08 PM

Not the Duck surely not the Ducky they like water not wine!!!
I have read when he got a little whiny but wino no way!!! :-}

-- An Index Of My Model making Blogs

View LittleBlackDuck's profile


5800 posts in 1704 days

#7 posted 09-15-2017 10:58 PM

... probably wine induced.

- Upgrayedd

BINGO! My expensive therapists are vino merchants!

I’m not an alcoholic... I’m a drunk... alcoholics go to meetings!

... they like water not wine!!!

- htl

This Duck never learnt to swim… The alcohol keeps evaporating before I can get my feathers wet!

-- If your first cut is too short... Take the second cut from the longer end... LBD

View Pjonesy's profile


384 posts in 1709 days

#8 posted 09-16-2017 02:09 AM

You’ve done it again Ducky. I agree with you that normal splitters (riving knives) are a bad design as we all seem to throw them out as they only get in the way.

-- Don't tell me it can't be done.

View LittleBlackDuck's profile


5800 posts in 1704 days

#9 posted 09-16-2017 11:54 PM

Thanks for the suspender belt (hidden support), PJ.

There are far too many woodies that have surrendered their ”splitters” for comfort and endangering their midriff. While built in riving knives should be mandatory, we with economy tablesaws, don’t share that luxury. After a 120×19 mm tattoo across my ample belly, I have summarised my views and become an acclaimed, awesome, avid, abhorrent, abject, advocate of a splitter (and any other ”A”s that may befit the topic).

If I can leave this blog with a message… incorporate a ”splitter” in your TS or spruce up you gut for an uninvited encounter.

-- If your first cut is too short... Take the second cut from the longer end... LBD

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