Making A Zero Clearance Insert For The Miter Saw Homemade Machines & Jigs
It’s funny how often this happens: I go out to my shop to start one project, and get sidetracked and end up making something completely different. That the case here, where I was looking around for scrap plywood big enough to do it with, and found my now defunct zero clearance fence for the miter saw. Since I’ve rebuilt the miter saw station, and that fence was made for the old one, I no longer need it. But, it did get me thinking on how I could replace it.
To start off, here is a video I did showing the assembly of the insert from start to finish:
To get started, I removed the plastic inserts from the saw bed and ground both to form a wider slot at the end:
Then I cut a strip of softwood to fit into the gap and added tabs to the end to lock it in place:
That takes care of the bottom and also stops the empty space under the plastic insert from filling with dust and bits of off cut wood.
Here’s where it gets interesting: I had an idea to make separate inserts that fill in the big opening in the fence, that will just slide in and out as needed. These would be a lot more handy than the big one I originally made, since they would be small, easy to install and (most importantly in a small shop) easy to store.
I started by marking a piece of 1/2″ plywood to fit in the space in the fence:
Then cut it out on the scrollsaw. For the 90 degree one, nothing else needs to be done with it, but for the 45 degree insert, it needs to be cut to clear the fence on the saw as it slides out (this is shown more clearly in the video above). That can be done a number of ways, but I used the table saw with the blade raised about an inch and carved the wood away:
The next part is made from solid hardwood and fit under the part that hangs down on my saw. I used my mini table saw sled to make the notch:
I then cut it to 45 degrees exactly the thickness of the 1/2″ plywood behind the fence, then tested the fit. The plywood should be flush or just slightly inset:
Two more pieces of plywood go on either side of the hardwood block and fit snugly around that part of the saw.
I had to notch these on the 45 degree one to clear the fence:
This needs to fit on tightly, since the insert relies on just friction to hold it in place. Better to make the space undersized, then fine tune the fit by sanding it until it just slides on:
I used fast setting epoxy to join the fence insert, since wood glue will not be as strong for end grain. No mechanical fasteners were used (like screws or nails), so these glue joints need to be strong.
Next, I added a block to the top and set in a small screw to adjust the fence forward:
It bears on a solid part of the frame (red arrow) and will allow fin adjustments. This is important – the insert needs to bear solidly up higher on the saw frame like this for safety:
I need to point out that there is some engineering involved with how this works and if you don’t feel confident that you can adapt the idea for your saw, you should not. The spinning blade can grab the insert (if it’s not properly made) and hook it up, causing a very dangerous situation.
First cut on the 45 degree insert went smoothly. The 90 degree one installed (but not yet cut):
I made a plug for the wider slot at the end as well. This can be removed easily by threading a screw part way into the hole to pull it out:
This picture shows how much of the solid hardwood block is still uncut. That’s another important thing – there needs to be enough left to hold the assembly together securely. After that first cut is made, it would be a belt and suspenders approach to drill a hole and glue a dowel across the uncut area to further reinforce it:
I get the feeling that I’ll be using this a lot more than the one I had before!