I recently went out purchased a Ridgid R4512 table saw and needed some zero clearance inserts (ZCI), but at $30+ an insert I decided to take a crack at making some. Anyone who has this saw knows that these inserts are a little tricky as there are a number of small pockets where the leveling screws rest and the insert must be cut out to accommodate them. Also, there is a slight bevel just inside of the throat so the insert has to have a very thin lip around it.
As I started looking at how to make a ZCI I knew a template would be the way to go! I created the first insert by using the original insert screwed to a roughly cut blank and using a flush trimming router bit very carefully routed a matching copy. Having a exact copy of thicker material makes it much easier and more accurate to make duplicates.
I’m sure there are other ways to do this but this is what I came up with and I thought I’d share it with anyone who has this saw and is looking for a fairly quick and easy way to make accurate ZCI’s
What I came up with was two templates. Here they are screwed together for storage.
Here are the two templates. One is to create the outside perimeter while the other to route the recessed pockets.
Screwing the first template to my blank I trace the outline and drilled small holes through the template into the blank, marking the center of the pockets. I used the original insert that came with the saw to determine the location of these pockets on the template.
The green circles are where I drill through the template and into the blank to mark the location of the pockets.
The orange circles are where I screw the template to the back of the insert blank.
Once you have the location of the holes marked and the outline of the insert traced you can remove the template and using a bandsaw/jig saw cut away the excess material leaving a 1/4” or so of material on the outside of your line.
Here you can see where the holes are circled on the blank.
Even in a blurry picture you can see a couple of the pockets that have been bored out with the drill press laser set up to drill out the next pocket. Using the small holes as a reference, I used a 1 1/4’ fostner bit to drill about 2/3 the way through the material. You will use the other template with the router to fine tune the depth of the pockets.
After the holes are bored and the excess material is cut away from the edges, re-attach the blank to the template and with a flush trimming bit route to create a perfect match.
Now switching to a second flush trimming bit with the bearing on the bottom and the second template attached sneak up on the underside of the pockets until you are to the depth you need for your insert to sit flush or slightly recessed. A caliper comes in very handy to identify this measurement so that you will know it for all your other inserts. The thickness of mine is 0.100”
With the pockets cut to their finished depth (height) remove the template and reset the router bit so that is just brushes the underside of the pockets. Setting the router fence so that the bit sits roughly 1/8” proud and leaving only enough of a gap between the fence for the bit to spin freely route the edge of the insert. This will leave a lip on the surface of your insert making it sit nicely into your table!
At this point the plate should fit nicely into the throat of your saw. Depending on the thickness of your material it may rest on the blade though.
To mark the location where the blade makes contact I removed the riving knife and replaced the 10” blade with a smaller 8” blade. Cutting through the insert as far as I could with the smaller blade I then laid the original insert over the new one and marked both the front and back edges of the opening. Because of the the riving knife you need to create a larger opening than can be done on the saw. I used a 1/4” straight bit to route the opening.
After making a couple of these I decided to route the saw blade opening into the template making it easier to set up the depth of the fence and the location of the stops.
It should be noted that because the weight of the material I use, the insert stays in place without needing any additional fasteners. Some may be uncomfortable doing it this way and want to fasten theirs a little more securely.
I hope this helps anyone who is looking for a cheep and easy way to make quick as well as accurate ZCI’s
(Oh, I didn’t put a finger hole in this one as I’m going to use it for my dado stack and the opening will be sufficient to be able to remove it.)