Why would you need a ZCI? (If you know why, you can skip this part)
If you suffer from tear out when you are cross cutting with your miter saw or needs to cut small/thin pieces that risks getting stuck in between your blade and cutting area you might consider to make a zero clearance insert to better your results.
You can make a zero clearance insert to your table saw or bandsaw. This time I make one for my miter saw.
Most simple and cheap miter saw comes with a blade with few teeth and a large gap where the blade sinks into the saw bed. This is all good for construction work, like framing houses. Sawdust doesnt clog up your saw and the blade with fewer teeth cuts faster.
If you want a very simple solution you could just put a thin board under, or even use tape for occasional cuts.
Anything that supports the material you are cutting will hinder unwanted tearout. So for a even quicker solution stack your work piece on to a sacrificial piece.
But if you need to cut a lot and just want a little more long term solution, you could do something like the one I did here.
- I use masonite board. But you could use plywood or thin strips of other hard wood.
- Wood glue, sanding block, ruler, pen, clamps and a drill.
Step 1: Cutting a New Insert
I removed the orignal plastic brackets. Then I cut a couple of pieces of masonite to fit into the saw bed. I sand it so they fit as snug as possible.
I had to use my hand saw with miter box, because... well... My miter saw was "under improvements".
I used the original plastic brackets as template to drill new holes for the screws.
Step 2: The Glue Up
To get the right thickness of the insert, I glued two boards of masonite together. Clamped them and left to dry. Ater they dried, I then hand sand it to the final thickness.
Step 3: The Insert in Place
I used the old screws to fasten the insert in the slot.
Step 4: First Cut (is the Deepest)
After the insert is secured, I carefully made a straight cut with the saw. Let the saw blade cut. Never force it.
The last picture is a test piece (pallet wood of course!), with only small tear out on the short side (farthest away from the camera in the photo). For me and my work, this is quite acceptable, but one could also make a insert to accomodate that too.
A very long instructable for something that may be very easy to do and may be self explanatory.
But one frustration I know of, when I just started woodworking projects was just crappy cuts. It affected the whole projects sometimes. This might help someone.
And remember when doing other cuts to use a sacrificial piece (or even tape) to make cleaner cuts.
In the Instructables Woodworking Class lesson 2, you will also find a great bunch of info about tearout and Zero Clearance. https://www.instructables.com/lesson/Making-Perfec...