Does a miter saw zero-clearance insert make a difference?

Saturday, August 10, 2019

Does a miter saw zero-clearance insert make a difference?


Does a miter saw zero clearance insert help with tear-out? In this episode of House of Hacks, Harley shows how to make a miter saw zero clearance insert and then demonstrates the results, showing before and after cuts.

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For a written transcript, go to Does a miter saw zero-clearance insert make a difference?

Music under Creative Commons License By Attribution 3.0 by Kevin MacLeod at
Intro/Exit: "Hot Swing"
Incidental: "MTA"


Are you getting tear out from your miter saw cuts?

There's two theories as to why this is.

One says it's a dull blade.

The other says it's because you're no using a zero clearance insert, like me.

I've got the original OEM insert.

Today I want to try to test out that theory and create a zero clearance insert and see how well it works.

Zero clearance inserts are an easy afternoon project.

It's really just a piece of wood, cut to the right shape and thickness.

Put in the saw and a kerf cut in it with the blade that's going to be used in the saw.

This means that there's zero excess space around the kerf for things to fall into and in theory it helps support the wood so there's less tear out.

Because it's an easy afternoon project, I want to test this theory.

I've got a piece of old wood flooring from a previous project that I want to use to create a zero clearance insert for my miter saw.

But first, if we're just meeting, I'm Harley and this is the House of Hacks where I make stuff out of wood, metal and other similar material.

I'm going to be using a bandsaw to cut this to rough thickness and then a planer to get it to the exact thickness.

I'll also use the bandsaw to cut it to shape.

But if you don't have a bandsaw or a thickness planer, you can use hand tools: planes, files, sandpaper and a hand saw is really all you need to create one.

So, don't let not having certain tools stop you from doing a project.

Figure out a way using what you have to make due and get the project done.

Before starting this project, make sure the saw is unplugged.

First we need to remove the old insert. This will be used as a pattern for the new one to get the right thickness and the right shape.

It's held in by six screws. The last two screws are back here behind the fence and they're easiest to get to if the table is rotated to 45 [degrees] to reveal one screw and then the other 45 [degrees] to reveal the other screw.

And once the screws are removed, it just slides straight out.

Now that I have the plate out, I'm going to put it flush with the wood and make a mark for the thickness and then I'll put it on top and mark the outline.

OK. I have the bandsaw setup with the fence so that I'll get a cut a little bit thicker than I'll need and then I'll sneak up on the exact thickness with the thickness planer.

OK, again, this doesn't quite fit because I cut it oversized intentionally so I could sneak up onto a perfect fit using the sander..

OK, let's give this a test fit. It's looking really good actually.

Wow. I'm really pleased with that. There's no discernible movement in that whatsoever.

It's a really nice test fit.

I was wondering about putting the screws back in it and as tight as it is, I don't think I'm going to bother.

I'm going to see how well it works as it is.

It's time now to put a kerf in it and then do a test cut.

So, did it make a difference?

Let's take a close look and find out.

So, this is an interesting result.

Here's the original OEM insert with the old blade.

And here's the zero clearance insert.

To me, there's no real discernible difference. The look pretty much exactly the same.

Now, just for test purposes, I put a brand new blade on and used the original OEM insert and it is much, much cleaner.

So that tells me that the blade makes a much bigger difference than the zero clearance insert does.

Lesson learned: always have a sharp blade if you care about tear out.

I'll see you over here in these videos that YouTube thinks you'll enjoy.

And until next time...

Go make something.

Perfection's not required.

Fun is!