Old Unisaw + new Ark Shark = different way to make ZCI

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Forum topic by hairy posted 05-13-2018 07:52 PM 1001 views 1 time favorited 2 replies Add to Favorites Watch
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3004 posts in 4141 days

05-13-2018 07:52 PM

I recently joined the Ark Shark club. I might write a review, but it wouldn’t be as glowing as most, at least at this point. To be fair, I need to spend more time using it, there is a learning curve. Still, it is a very good product.

After installation I needed to make a ZCI. It was trial and error, emphasis on error, but it all worked out in the end. I made 4 blanks and finished 3 inserts. This first pic is the 2nd insert made, the other pics are from 1 and 2.

This is what I’m going with so far, subject to change as needed.

This shows the adjustable riving knife at it’s lowest point, minus the guard. Almost 3/4” sticking up. This will take a little getting used to. I like to leave my tablesaw bare when not in use. Sometimes it’s an assembly table, sometimes I put down cardboard and paint or apply finish, I like having a flat surface available . I have an idea, but I’m not ready to start cutting yet. But this is about the ZCI, not the Ark Shark.

I started with a blank 1/4” wider than the throat plate, marked where I wanted to stop the cut, and turned off the saw when I got there.

Now with the blade raised, I put in a factory plate, put my blank on top and then a ZCI on top of the blank, using the saw blade to keep everything aligned. At this time I traced around the blank to show where to rough cut on the bandsaw.

Before cutting the rough shape, I glued a spline into the saw kerf to fill in the gap, a bridge. I had no idea how big, so I started with 3/8” long.

Next I made another sandwich on the tablesaw, with the factory plate on the bottom, an aftermarket ZCI in the middle and the blank on top, with double sided tape between the aftermarket and blank. I found out d/s tape sticks to the top of the aftermarket, but not so good on the bottom side.

I’ll skip the pics about using a flush cut bit on the router table to get the final size, but I did have a surprise when I got the tape off and got a look at it. That’s not much of a bridge.

I glued in another spline, and later had to shorten it after it was glued in.

The plates I use have either a pin or a hook to keep the insert from lifting. I marked, drilled and inserted a finishing nail, and later had to remove it. I couldn’t get the insert over the ARK with the pin in.

I used a drill bit to mark where to drill for adjusting screws. After tapping I soaked the threads with CA glue, and retapped when the glue dried. I’m using 1/4” x 20 tpi allen screws. I am surprised how well 1/2” BB ply takes threads.

I cut 1 and 1/2” fingerholes on the drill press. Between 2 fences and 2 stops, the only way it can move is side to side. I kept overlapping the holes by maybe 1/16” to 1/8”. It took a while but left a nice clean hole . I can adjust the riving knife height with the plate in and the guard on.

ZCI #2 got a 5/8 ” long bridge, #3 got 3/4” . 5/8” seems to be the sweet spot. Easy to get on and off without hitting the ARK.

Here’s the final product installed.

I watched many youtube videos on how to DIY a ZCI. THANKS to all who posted those videos! The majority cut the ZCI to fit the saw, then raise the blade up through it to cut the slot.. There are a few that make the ZCI fit the saw, then cut the slot on top of an existing plate against the fence. I cut the slot first, then made it fit the saw. I’m sure there are other ways, this works for me.

-- Genghis Khan and his brother Don, couldn't keep on keeping on...

2 replies so far

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153 posts in 2655 days

#1 posted 05-14-2018 08:13 PM

I just sold my Unisaw that had a the ARK on it. It was useful. I wouldn’t have the used the saw without it. I made my ZCI using an 8” dado blade. That made most of the cut and I think I did the rest on the router table, cant remember. I used a $10 1/2” thick hdpe cutting board from walmart, made a regular and a dado. I don’t think I bothered with the front tab. Mine never lifted.

The one thing I wished I did was take the riving knife out and cut the slot through. This way you can take it out on certain cuts. Lee, the owner of, told me they made it that way just in case someone raises the bled it INTO the riving knife it won’t catch it toss it. I think the clamp is strong enough not to do that anyway.

All in all a good addition to an old saw. Their guard is great though.

View hairy's profile


3004 posts in 4141 days

#2 posted 05-15-2018 01:51 AM

I got the Ark to go down all the way like it should. It was hitting the washer on the bottom mounting bolt. I tried a smaller washer and it still hung up, so I took it off. I might take it all off and grind the Ark a little where it hits.

Maybe it’s not plumb, I’ll play with it some more. When I installed it I placed a framing square up against the saw blade and the Ark, clamped the square to the table, clamped the Ark to the square and tightened the bolts. I brought another square up to the other side to check. It looked good to me.

-- Genghis Khan and his brother Don, couldn't keep on keeping on...

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