Hillbilly’s Ultimate ZCI

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Project by HillbillyShooter posted 06-09-2014 02:55 AM 3834 views 9 times favorited 18 comments Add to Favorites Watch

The recent acquisition of a Magic Molder head and some cutters ( ) from my buddies at Ballew Saw & Tool here in Springfield ( ), prompted me to move forward with this project. I made seven Zero Clearance Inserts (ZCI) when I first got my PM66 back in 1994, but have discovered the value of using them since joining LJs a couple of years ago. The last three are now history.

The question of what would constitute a ZCI with everything I wanted has been rambling around during these past two years. The top two things are a red formica top and the ability to level the insert from the top like the factory insert. Next would be a jig system to speed up production of identical ZCIs, and allow for production of more ZCI in the future if needed.

The first step was to design a way to drill the finger holes at the exact same location on each insert (photo 2) and use one insert blank as a template to align each insert for trimming to exact size (photo 3) and drilling for the adjusting screws (photo 4) and a hole for the Biesemeyer splitter/anti-kick back attachment behind the blade when ripping. (photo 5)

There was a piece of 3/8” Baltic birch that I had on hand measuring 30” by 42-1/2”, so I covered one side with red formica and the other side with gray formica (both sides have equal stress this way). I used threaded coil inserts in the adjustment screw holes. I should now have enough blanks for a while. (photo 6)

As always, comments (good, bad, critical or whatever) are greatly appreciated. Thanks for looking.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

18 comments so far

View doubleDD's profile


9637 posts in 2890 days

#1 posted 06-09-2014 03:22 AM

Those are some of the best looking inserts I have seen. Very professional. I think covering both sides of the baltic birch will keep them more stable. I like your new catch on the stringer. Looks like you have been doing more than woodworking. Glad to see you are enjoying life.

-- Dave, Downers Grove, Il. -------- When you run out of ideas, start building your dreams.

View TNwoodchuck's profile


102 posts in 4622 days

#2 posted 06-09-2014 03:23 AM

Very nicely done! Isn’t it great when a plan comes together.

-- Chuck near Nashville - “All you are unable to give possesses you” (Andre Gide)

View a1Jim's profile


118134 posts in 4424 days

#3 posted 06-09-2014 05:01 AM

Boy your really cranking those puppies out.nice work


View luv2learn's profile


3073 posts in 3150 days

#4 posted 06-09-2014 05:17 AM

I had not thought about covering both sides of the insert with Formica, thanks for that tip John. Also, thanks for showing us the cool template you made to get accurate repeatability for the adjustment and finger holes as well as using it as a router bit guide.

-- Lee - Northern idaho~"If the women don't find you handsome, at least they ought to find you handy"~ Red Green

View whitebeast88's profile


4128 posts in 3037 days

#5 posted 06-09-2014 07:01 AM

great job.thanks for the tip on covering both sides with should have enough zci’s to last for a little while at least:)

-- Marty.Athens,AL

View Roger's profile


21030 posts in 3651 days

#6 posted 06-09-2014 11:40 AM

Fantastic John! ZCI’s are a necessity. These will surely give some non-tearout results. These will last a long time as well. Gr8 stuff!

-- Roger from KY. Work/Play/Travel Safe. Keep your dust collector fed. [email protected]

View Jim Jakosh's profile

Jim Jakosh

25177 posts in 3952 days

#7 posted 06-09-2014 11:56 AM

Very nice, John! Great way to mass produce them!! You may be getting orders!!
I have a Ryobi saw with a rectangular insert and it not so easy to make one to fit.
Thanks for sharing!!!!!!!!!
Nice job!!..................Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View bigblockyeti's profile


6719 posts in 2568 days

#8 posted 06-09-2014 12:33 PM

That’s quite a few ZCI! Laminating both sides does sound like a good idea, the threaded inserts sound like they might be overkill. I’ve just used set screws right in the wood, seems to work best if you let the screw cut its own thread for a nice tight fit.

-- "Lack of effort will result in failure with amazing predictability" - Me

View HillbillyShooter's profile


5811 posts in 3139 days

#9 posted 06-09-2014 12:40 PM

Thanks guys. Also, I have to confess the idea of covering both sides with Formica to reduce stress came from one of LJ’s box making gurus who pointed out the need to cover both sides of BB with veneer (sorry I can’t remember the source).

Too bad each saw uses a different size and design for its insert, or I’d be glad to share, Jim.

Dave: thanks for noticing my stringer. I’ve wanted to be a fly fisherman since I was a kid visiting Colorado in the summers. Maybe with a little luck I can call myself a real fly fisherman in another 10-years.

BBYeti: I tied it with and without inserts. And, with inserts worked better for me as the without insert proto-type had the set screws back out when I ran it through the router table to ease the edges.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

View kiefer's profile


5760 posts in 3514 days

#10 posted 06-09-2014 01:05 PM

Nicly done John .
Good setup with the jig you built to make it easy to make another batch as they will not last forever and there is a need for one with every different blade or cutter and tilt setting .
Yes always cover both sides of the material used like a door with laminate as it will warp otherwise .
You are referring to HELI COILS I think for the inserts not threaded inserts ?

-- Kiefer

View Ken90712's profile


17902 posts in 4036 days

#11 posted 06-09-2014 03:24 PM

Great work, thx for sharing. I’ll have to use this idea when making my next batch…. Awesome.

-- Ken, "Everyday above ground is a good day!"

View HillbillyShooter's profile


5811 posts in 3139 days

#12 posted 06-09-2014 03:48 PM

Klaus—thanks for the HELI COIL clarification. I seem to remember that was the original name for the inserts but the brand I used was Perma-Coil and I have others branded as Perma-Thread.

Ken—thanks and good luck.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

View NiteWalker's profile


2741 posts in 3424 days

#13 posted 06-09-2014 04:54 PM

Great job with the inserts; I love the jig for batching them out. :-)

For leveling, I used to use set screws, but now I just use 1/2” 8-32 machine screws.
I drill a hole smaller than the threads and when the machine screws are driven in, they cut their own threads and have a nice tight fit so they don’t move with vibration.

-- He who dies with the most tools... dies with the emptiest wallet.

View MarkTheFiddler's profile


2068 posts in 3035 days

#14 posted 06-10-2014 02:58 AM

John, those inserts are art. I was going to post a miter sled. It looks like a slipshod hunk of trash compared to those beauty’s. very well done sir!

-- Thanks for all the lessons!

View bluekingfisher's profile


1333 posts in 3827 days

#15 posted 06-13-2014 08:48 AM

Nice work John, I particularly like the innovative way you created the back slot for the original spliiter. On mine, I had several issues so I just cut a similar slot and inserted a slither of hardwood about 40mm long and 5mm high, which allows me to keep it in place while conducting joinery work.

I have seen various ways for allowing for level adjustment although the best way I found was to use brass hex head insert grub screws. Far less likely to cause harm to the lug plates using brass.

The downside of ZCI is the amount of dust they permit into the shop due to the tight fit of the blade slot to the blade where DC can’t function to its full extent . In an attempt to counter this, I drilled an 18mm hole at the very back of the slot where the blade teeth emerge from the throat plate on the up cut. This allows the DC to draw the invisible dust particles back below the table and not into the air. Although not so much of a concern with the moulding (molding) head cutter. When are you guys going to write in English lol.

The HP Formica makes it look the part too.


-- No one plans to fail, they just, just fail to plan

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