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Last updated on May 14th, 2020 at 12:40 am
A miter saw, circular saw, cut-off saw, radial arm saw, and a table saw have one thing in common; they all use circular saw blades to cut. These power tools use circular blades to cut wood. Each has a motor that rotates the saw blade at a high speed enabling it to cut wood quickly and fast. Some of the common woodworking cuts you can make with power tools that use circular saw include a cross-cut, rip cut, miter cut, and a bevel cut. A sharp blade ensures that you end up with very clean and accurate cuts. Otherwise, you may end up with ragged and ripped cuts. Sometimes a blunt circular saw blade causes so much friction that results in burnt cuts.
It is always good to inspect your circular saw blade for dullness before putting it to use. This ensures that you replace or sharpen it ahead of time to avoid wasting time and making ugly cuts. It also saves your tool from laboring a lot when cutting thus increasing its life. For inexperienced woodworkers, it can be difficult to tell when a saw needs to be sharpened or replaced. Fortunately, there are some telltale signs of a bad circular saw blade saw you can easily identify when cutting wood. In this article, I will share with you common 10 signs of a blunt circular saw blade. Reading these signs will help you plan a replacement of the saw blade on your mitersaw or circular saw ahead of time. Alternatively, the signs will help you know the right time to sharpen the cutting blade.
10 Common Signs of a Bad Circular Saw Blade
The following signs will help you know when to sharpen or replace the cutting blade on your circular saw, chop saw, or table saw so that you can continue making clean cuts.
Blade starts chipping wood
Chipping or tearing out of wood occurs mostly when cutting across the grain direction of lumber or sheet of wood or plywood. As the saw blade exits wood material, it lifts up little pieces of the wood grain. This causes the wood material to splinter at the cutting point resulting in ugly edges. Although chipping o wood is one of the characteristic signs of a blunt saw blade needing replacement or sharpening, it can also be a sign of a badly positioned lumber or plywood. Therefore, before you decide to slap in a new round saw blade, you need to ensure that you are using the woodcutting best practices.
One of the best practices of cutting across the grain of wood material is to scribe the cutting line before running the saw. You can use a utility knife or a cutting gauge. By scribing wood or precutting it using a scribing tool, you savor fiber ahead of time so that when a sharp saw blade cuts, you have a nice clean edge. Alternatively, you can apply masking tape on the top side of the wood that will be cut. Another trick that applies mostly to plywood is to cut with the best side facing down. This way, you prevent the teeth of the blade from grabbing and tearing out veneer when exiting. Otherwise, if you are still getting ugly rough edges, I would advise you to sharpen the saw blade or replace it with a new one. Torn out wood edges are ugly and unprofessional. Don’t let a dull blade undermine your woodcutting skill!
Cutting wood becomes hard
Unless your electric wood saw tool is not powerful enough, one of the sure ways to tell that a cutting saw blade is blunt is if it struggles to cut through wood material. You will also notice that it takes longer to cut and you have to apply a lot of force to push it through the cut. A brand new circular saw blade cuts through wood like butter.
The cutting blade spins slowly
As it gets harder to cut through wood with a dull saw, the speed of rotation of the blade reduces significantly. When the blade spins very slowly, it can cause friction to build up making it extremely difficult to cut through. A blunt blade is very ineffective and may degrade the quality of woodcuts by leaving burn marks. It may even cause the motor to labor a lot resulting in overheating. Overheating the motor reduces the life of the tool.
Although a blunt blade is a major cause of slow spinning, using the wrong saw blade can also cause it to cut through slowly. For example, a cross-cutting blade spins very slowly when used to make rip cuts. Therefore, you should make sure that your circular saw, miter saw, or table saw has the right blade for the type of cut you want to make.
In addition to spinning slowly, a dull round saw will cause the tool to labor you cut through wood material. If this continues, the motor and the blade may overheat. Sometimes a laboring sound may be produced if the saw contacts material to be cut before getting to full speed. It can also occur when you start the saw with the blade against the wood to be cut. A laboring sound is usually a sign of a saw that is struggling to cut. Detecting a laboring sound, however, requires a trained ear to tell when the machine is working harder. Newbies might not differentiate and it would be advisable to look at visual signs.
Cuts become ragged and burnt
As mentioned, an unsharpened saw blade will not only cause the motor to overheat but also the blade due to buildup of friction at the point of contact. This results in ragged cuts with burn marks. Marks of burning on woodcuts are very visible and make your work look ugly and unprofessional. You can avoid them by ensuring that the circular saw blade you are using is sharp enough to cut through wood easily and quickly.
There are other reasons why wood would have burn marks on it when cutting with a saw blade. One of the reasons is a dirty blade. The teeth of a circular blade must remain shiny. So, when they start to discolor, that is dirt building up and will cause friction to build up when cutting. This results in burn marks on lumber. You can avoid having dirty blades by cleaning regularly with a tool cleaner fluid for removing wood resin and a soft brush such as a toothbrush. This will keep the blade shiny and cutting as good as new before it gets dull. On a table saw, the circular blade might cause burn marks on wood if you feed the stock too slowly or if the table saw fence is misaligned. So, you must ensure that you are feeding lumber at the right speed and that the fence is parallel to the table saw blade.
Smell burnt wood
Sometimes it is easy to mistake small burn marks with wood contours. If you doubt that the dark edges are as a result of burning or heating, you can validate with the smell of burnt wood. Usually, when wood overheats due to friction, dark areas are formed at the point of contact and a burning smell is produced. This smell is close to that of toast. When you smell it, you should know that your wood is cooking and it is time to inspect the blade.
If you are wearing dust mask, it might be difficult to smell burning wood. However, you cannot fail to see smoke when it appears. Sometimes the heat due to the friction between wood and a blunt saw blade may produce visible white smoke. This is a sign that the blade needs your attention. You should not wait until you cannot see the cut to sharpen or replace the cutting saw blade.
Cut quality degrades
Woodcuts made with dull saws are rough and very ugly. A feel by hand will tell you that something is not good with the blade. But you also need to ensure that you have positioned wood material in the correct position while you make cuts.
Blade can no longer be sharpened
After intensive use, the teeth of your saw will eventually wear out to a point that they cannot be sharpened anymore. In such a case, you will need to replace the blade with a new one. Otherwise, sharpening totally worn-out circular saw teeth will not give you clean woodcuts. Sometimes if getting a professional sharpening service is impossible, it is best to buy a new sawing blade for your machine instead of trying to sharpen it yourself. You know the work of sharpening saw blades requires attention to detail for you to get substantial results. In fact, I recommend using a digital sharpening device if you are going to sharpen your saw blade. This ensures that you get a factory equivalent sharpening job, especially on carbide-tipped round sawing blades. If that is not possible, you better invest in a new blade altogether.
Missing teeth on the circular saw
Sometimes when cutting with a circular blade saw you may encounter hard surfaces that may break the teeth of the blade. Dropping your saw blade on a hard surface may also result in broken saw teeth, especially for tipped teeth. In such situations, the only thing you can do is to replace the blade with a new one. Otherwise, installing a blade with a broken tooth or chipped teeth on your saw machine may cause injury and often results in substandard woodcuts.
Bottom line, if you want to maintain crisp and clean woodworking cuts, you need to know when the saw blade starts to fail. This will help you sharpen or replace the blade ahead of time before the quality of cuts begins to degrade. These 10 factors will help you a great deal to identify when the blade in your sawing machine starts to give up so you can act accordingly. Lastly, if there is a symptom of a bad saw blade I have missed, please feel free to share it in the comment section. This will help to keep the circular saw tools in optimal conditions throughout.