Miter Saw Setup for Accurate Cuts

I really demand a lot of my miter saw when I'm makin' face frames, when I'm makin' cabinet parts, when I'm making furniture parts, of course, walk up to the saw, make a cut. We expect that cut to be square or a perfect 45 or a perfect 22 and a half. So what we're going to talk about here is the approach that I take to checkin' the saw and make sure it's doing everything I need it to do. And I'm a big fan when I'm setting up tools of doing it under power. What I mean by that is I don't want to just lay a square on the saw and check from blade to fence. I want to make a cut and I want to find an approach that's going to really let me double triple check that cut to make sure it's dead accurate. So let me show you what I'm talking about. I've got some boards prepped and you'll see on the boards that I've got an X. That X indicates an edge that I've jointed. So it's key for this to all work that we know this edge is perfectly straight. And when we do what we're about to do that perfectly straight edge has to go against the fence on the saw. Now, when you're doing this test, the wider the boards, the more accuracy you're going to have, and that'll make more sense in just a second here. So first thing, I'm going to cut two boards, with their jointed edge against the fence, and then I'll show you where I'm going with this. Now keep track of what just happened. I cut this end and this end. Now generally what I do is I take these boards to my jointer or my table saw. I'm looking for a dead flat surface in my shop. I've got this big slab, it's an old countertop piece that's really heavy, really flat, so we can do the same thing here. What we want is jointed edge down on the table and then cut to cut and kiss them together. And what's amazing about this. What I really love about this is it gives us the opportunity to really magnify any error that the saw has. So here's what's going on in this case. And what I actually did here is I tweak the saw out of square so that you could see what I'm looking for. They're touching at the bottom, they're open at the top. Now they're only open, what, a 16th of an inch. So that means over the travel of that cut, each cut was off by half that amount, a 32nd of an inch. So when I talk about how this amplifies any error that we have, that's what I mean, we're seeing two times the error, so I tweaked it out of square, so you could see what I'm looking for. So then what you need to do is go to your owner's manual and check what do I need to do on this particular saw to get it to that perfect 90. Do another test cut, check it, do another test cut. So generally it takes me two or three cuts to get this perfectly, perfectly, perfectly where I want it. So a couple keys to making that work. Jointed edge, so it's dead straight, jointed edge goes against the fence, wide boards, so that we're working across a big area. That'll take care of setting us for perpendicular. Now what's great about miter saws these days, with their detense, is that when we set this for 90, and then we switch, 22 and a half, 30, 45, that we're automatically going to get the accuracy we want out of those other cuts. So it's really critical that we get this 90 degree cut right. This method is going to get you there. So make that adjustment. Now, the other thing is that when we've got saws that are capable of tilting their head, like this one is, then we also want to make sure that we're cutting 90 degrees in this direction. We're going to take a real similar approach. Narrower boards, because my capacity vertically is less than my capacity horizontal. Same idea though, jointed edge down on the table, make a cut twice. See what we have. That end of that one. That end of that one. Now, one of the things I do want to point out is there's my jointed edge but when I turn this so that I can touch ends that jointed edge is on my side, not your side. So it's still down on the surface. And then we do the same thing. Let those ends kiss , look for any gaps that you have between the two boards. When you don't have a gap, like this, then you know you're cutting dead perpendicular to the table. So this is a great way to check your miter saw in both directions here, make sure it's doing what you want it to do, make sure it's making those accurate 90 degree cuts. And then you're going to get accurate angled cuts as well and accurate beveled cuts when we tilt the head on this. Make sure you go through this process and your saw is going to be treating you well so that you get that accurate cuts out of it.