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A miter saw is one of the most reliable electric saw cutters for making even cuts on wood. It is easy to use and safer than a table saw. Moreover, using a miter saw requires minimal effort to achieve precise and neat cuts.
However, sometimes a miter saw can cut unevenly and leave jagged edges and tear-outs on your wood. This can be frustrating especially when it happens on the wood you want to use to make some fancy furniture. And it begs the question, what can you do to prevent miter saw tearout?
To save you the frustration of trying to identify why your miter saw is splintering wood, I have summarized 11 possible causes of tear-outs and how to fix each one of them.
Table of Contents
What Causes Miter Saw Tearout? How To Prevent It.
The following are the 11 most common causes of miter saw tear out and their corresponding solutions.
1. You don’t sever wood fibers before cutting
Some people have no idea that a utility knife can be the difference between making a clean or a rugged woodcut on a miter saw. Yeah, if you score the cutline on the wood with a sharp utility knife you can prevent wood fibers from splintering. This is called severing the wood fibers.
All you need is a nice straight edge to guide your knife. You can use a ruler or a straight frame. Once you score the line on the face and edges of the board, the blade will not lift up wood fibers on its way out since they will be severed already. This will prevent splintering.
The caveat, however, is that you must line up the side edges of the saw blade teeth with the cut mark. Also, the kerf of the blade should be on the waste side of the board. The waste side is the side of the stock you will discard.
Cutting on the waste side ensures that you end up with the correct length of the board and that the edge of the good side is as smooth as you need it.
2. Cutting with the finish side down
Unlike a table saw blade that cuts stock from the bottom, a miter saw cuts from the top. This means that the teeth of the miter saw blade must face down to make the tool safe and to avoid injuries. As such, if you are keen you will notice that tearouts on the miter saw occur at the bottom of the stock as the blade exits. And this somehow answers the question of whether you should cut wood on a miter saw with the finish side up or down.
If you guessed properly, you should cut wood with the finish side up on a miter saw. This will ensure that any splintering occurs on the non-show face. But if you need a clean cut on both sides, use a backer board underneath.
Sometimes though, splinters can occur on the top side. To prevent this from happening, you can tape the cut line. That way, you will be sure that the fibers are supported and you will not have to worry about splintering on the show face. Unless your miter saw blade is bad or not the right one.
3. Using a blade with low tooth count
Another reason why your wood splinters on the miter saw is if you are using a blade with a low tooth count. Saw blades with low TPI cut fast but roughly. They are great for ripping wood.
So, if you want the edge of your wood to be as smooth as glass, go for a blade with a high tooth count. A good trim blade with at least 90 teeth or more will do a fine job.
However, more teeth mean you will cut more slowly. And this takes us to the next point.
4. Pushing the blade aggressively into the stock
Since blades with higher tooth count cut slowly, you need to be patient with the saw. Do not push the blade too hard into the stock. Just push it lightly and let the saw blade do the cutting. In other words, take your time and let the blade have time to do a better job. Slow down and get a 100-tooth blade for trim work
5. Cutting with low-quality saw blade
The blade on your miter saw might have the right tooth count but poor quality. For example, stock blades that come with the miter saw are often low quality and mostly for general purpose use, not for finish work.
For this reason, you need a high-quality finish cut blade. You can try the Diablo ultimate polished finish blade or use any blade from a reputable brand that has carbide teeth. And remember, even if you use a high-quality blade, it should have many teeth to produce a smooth cut.
6. Not using a zero clearance plate/using the stock plate
If you are using the zero clearance insert that came with the miter saw or not using one at all, it could be the reason your miter saw cuts badly. You need to replace it with a custom insert.
A custom zero clearance insert has a narrower slot and therefore supports wood fibers better to prevent fraying or splintering. It is one of the most important jigs even on a table saw. So, just replace the stock insert with a custom insert and you will see the difference. You can buy or make one yourself.
7. Not using a sacrificial board
For the miter saw to cut cleanly, you also need to “sacrifice something”. Not like you have to kill an animal and pour the blood in libation. No! I mean you have to put a sacrificial board underneath the stock you are cutting so that it is the last thing the blade cuts as it exits, not the stock.
A sacrificial board supports the fibers of your stock and keeps them from splintering. And if there is any tear out, it will occur on the board underneath, not your precious workpiece.
8. Forcing the blade to cut in one go.
As I said, when you want a clean cut, you must be patient with the blade. This not only means pushing the blade slowly and lightly but also trying multiple passes instead of trying to cut the whole thing in one cut.
9. Dust collector not doing its job
Check that the dust collector is doing its job so that dust does not accumulate on the mounting surface and cause the miter saw to cut badly. After every cut, always wipe off the dust before placing new stock. This enables the saw to slide smoothly and the blade to run true.
10. You don’t wait for the blade to stop spinning
After making the cut, wait for the blade to stop spinning before removing it from the board. If you remove it while it is spinning, it could lift up some wood fibers on the edge and cause tearout.
Another important thing about the spinning of the blade is that you should always let it attain maximum speed before bringing it down to cut. Similarly, if you are using a sliding miter, let the blade spin at full speed before sliding it forward onto the stock.
11. The wood is the problem
Lastly, some wood just doesn’t cut nicely. So, if you have checked everything on the miter saw and it is good but the cuts are still rough, the problem could be the wood you are cutting.
To be sure though, try to cut a different type of wood and see if the edge will be any smoother. If the edge is splinter-free, then you know the stock you are cutting is not that great and you need to change or fix it.
Wrap up
Well, those are the most common issues that could be making your miter saw cut badly and how to fix them. I have summarized the 11 causes of miter saw tear out and their easy solutions.
| Causes of Miter Saw Tear Out | Solutions |
|---|---|
| 1. Not severing wood | Score the wood before cutting |
| 2. Cutting with the finish side down | Cut with the good side up |
| 3. Using a blade with a low tooth count | Use a high TPI blade |
| 4. Pushing the blade too hard | Be gentle and let the blade do the cutting |
| 5. Bad quality saw blade | Use quality blade with carbide teeth |
| 6. No zero clearance plate | Use custom zero clearance insert for miter saw |
| 7. No sacrificial board | Use sacrificial board |
| 8. Forcing the blade to cut in one go | Make several passes with blade |
| 9. Ineffective dust collection | Improve dust collection |
| 10. Not letting the blade stop | Let the blade stop spinning before removing it from wood |
| 11. Bad wood | Change the wood if possible |
If the problem persists, you might need to call an expert to help you troubleshoot it. But if you are just getting started with miter saws, you may be needing a bit of practice to learn how to use them more effectively.
I hope this information helps you to make better and cleaner cuts on your miter saw.
