Burnt wood is very cool looking when you want that look. But what about the times you don't. What about those times you are making a cut and you see burnt marks from the saw?
There are numerous ways wood burns when you cut this material and we will go over all of them, but there are two main reasons why wood burns. The two main reasons are human error and machine error. If you can remember this, you can stop burning your wood. Yes, when it comes down to it, it is all human error because we control the machine, so we are at fault.
The first thing you should know is what exactly is wood burn. If you look at a piece of wood from a couple feet away, it just looks like one piece of material. However, when you really look close, you can see small fibers. These small fibers are what makes the large piece of wood. Wood burns because all wood is made up of small particles of fiber. All of these tiny little fibers combine to make the tree. These tiny little fibers have what is called an ignition temp. Ignition temp is at what point an item will burn. So in essence when you burn wood, you are creating enough heat to burn these little fibers at their ignition temp. So our goal is to not reach the ignition temp of the wood when cutting.
So what causes heat. Heat is caused by friction. So if we can reduce friction, we can reduce our wood from burning.
Let’s first start with the most common error, a dull saw blade. About 70% of the time when wood burns, it's because of a dull saw blade. A steel blade will dull extremely quick if you are cutting hardwoods. This not only will this cause the wood to burn but will also put more wear and tear on your motor. For hardwood, use either a HSS or Carbide blade. For a better understanding of saw blades, you can view our information page on saw blades. If you will be making a lot of cuts, it would be wise to invest in a couple HSS blades and carbide blades.
10% of the time burning wood involves your feed rate. Most people, especially new beginners, tend to feed the wood through the table saw to slow. One thing you have to remember is that table saws have a lot of power and are designed to cut wood at a fast pace. So when you are feeding the wood at a slow pace, the blade now has more time to rub against the side of the wood and burn.
One mistake that causes a slow feed rate is adjusting your hold on the wood as you are feeding the wood through the saw. When you are readjusting your hold, this tends to move the wood into the blade and causes an uneven cut. One pointer is to think ahead. Before you make a cut, think about how you want your hand positioned. This will cut down on the amount of time you need to readjust your hands during the cut. In regards to the feed rate, let the saw tell you how fast to feed the wood. If the saw is bogging down when you push the wood through, then your feed rate is too fast.
5% of the time, wood burns because of dirty saw blades. I know this sounds goofy, but when you think about it, it makes perfect sense. When you have dirt on your blade, this is what is touching the wood first before the blade itself. So what happens is the dirt heats up very quickly and subsequently causes the wood to heat up faster than if the wood was just hitting the blade. All you need to do is clean your saw blades with a little cleaner and spray with WD40 after you are done for the day.
5% of wood burn is due to the wrong blade on your saw. Just make sure you use a ripping, crosscutting or any other blade for the wood you are cutting. The are reasons a plywood blade has about 100 teeth and a cross cutting blade has around 48 long teeth.
A dull blade, a fast feed rate, wrong blade and dirty saw blades make up 90% of the reason wood burns, but that still leaves the other 10%. Well, the other 10% are not that common, but if the above three items do not take care of your problems, you can also check these following items to pinpoint why you are burning wood.
Check you blade height. A saw blade cuts two ways. If you have the blade height set at the same level as your wood, you will get a different cut than if your saw blade is set about 1/2? higher than the wood. When the blade is higher, you are cutting on the way down as opposed to cutting the front of the wood. Never go about 1/2? above the wood, you are working with as this can cause kickbacks and more problems.
Warped lumber is another item to look for. When you go to the lumber yard, always eye your wood to make sure you are not dealing with warped lumber. This will certainly cause wood to burn, but you shouldn’t be dealing with warped lumber in the first place. Someone once told me improperly dried wood can cause burns also. I agree if you are cutting the tree and drying the wood yourself. Nowadays, lumber yards have such good technology and equipment, rarely will they let the wood dry the wrong way or even let bad wood out of the yard, but I guess this is something to think about.
Another item to take into account is your splitter could be misaligned. A misaligned splitter would cause the wood to bind and not run straight, which causes more friction and can even cause kickbacks.
A warped blade will also cause more heat build up. When your blade is warped, it will move back and forth (Wobble) when cutting wood instead of a nice straight line. In return, this causes more friction and will cause wood to burn.
If all the above items fail, check to make sure your blade is parallel to your fence, make sure the blade is aligned with the miter slot. Lastly, your arbor Flange could run out. This will cause your blade to wobble.
As you can see, there are many different reasons why your wood will burn when cutting with a saw. The items you should first consider are Dull Blade, Dirty Blade, the wrong blade for the cut, or your feed rate.