I decided, somewhat on the spur of the moment, that I would finally make the zero clearance insert for my table saw that I have been meaning to make for years. It is something I should have done long ago, not so much for the reduced tear out when cutting sheet goods as for the increased safety of preventing thin off-cuts from falling in along the blade.
It turned out to be pretty straight forward though there were a few gotchas. For those that are interested, here is the process that I followed:
Sizing the blank
The first step was to cut the blank. I used 1/2″ Baltic birch plywood as it is straight, stable, smooth, and slightly less thick than the metal insert that came with the saw. FYI, the saw I have is a Rigid job site saw. Its a great saw with a lock for blade depth which is something that I was unable to find in any other job site saw. That may have changed over the last number of years however.
I set the fence to cut the blank to width by registering off the original metal insert.
And checked the width of resulting blank.
I then used the original insert to mark the curved ends at the end of the blank. The cuts on the end of the blank were made on the band saw followed by a disk sander and file to smooth and finish the edges.
I then test fit the new insert into the saw. It looks like it doesn’t fit but that is just because, on this specific saw, the blade doesn’t actually go down far enough to allow the new insert to sit fully in place.
Cutting the slot and additional features
In order to fully check the insert fit, I had to fire up the saw and have the cut driven up into the new insert. The result fit so well that I couldn’t easily remove it again so I also added a finger hole to pull it up and out if needed. Another requirement was cutting a keyhole at one end to accommodate the screw that holds the insert in place in the table top.
Leveling the insert
Its not really clear in the pictures above but, even though the insert is actually thinner than the original plate, it was still sitting proud of the table top. It turns out the that the trunnion assembly actually sits slightly closer to the top of the table than the rests for the insert that are molded into the table top. With the original insert, this wasn’t an issue as it was full thickness only at the edges. As the new insert is a constant thickness, it made contact with the trunnion assembly (seen to the left of the blade in the picture below) before it made contact with the insert supports.
The answer, while not elegant or pretty, was to use a chisel to remove a layer of the insert on the bottom side to provide the necessary clearance. If I make another insert in future, I may use a router to do a cleaner job of it. For now, it is on the bottom of the insert so not visible when installed.
As a result, the insert now sat level but below the level of the table. In order to correct this, I used the same strategy as in the original insert. I drilled 4 holes, one in each corner of the insert, and threaded them to accept grub screws.
With the screws in place, I am now able to adjust the insert to bring it up flush with the table. I also rounded over the edges just slightly to avoid any interference as stock moves over the insert during sawing.
That’s it – the insert is now installed and working great. I actually made a second one as well in case I need to either do dado stack or angled work with the saw, either of which would destroy my straight insert.
If I do this again (which I might now that I have the bugs worked out), I think I may use stock that has a composite surface to reduce friction and improve the finished look. But, for now, things work great so there is no rush on a replacement.
Thanks for reading!