What do you do with dull saw blades? Should you replace with a new one or is it worthwhile to sharpen a circular saw blade?
The answer is yes, it is worth sharpening a circular saw blade. Generally, blades that cost $50 or more are worth sharpening while it is better to replace cheaper, low quality blades. Re-sharpening the blades will reduce wastage and save you money in the long run especially if you are using expensive carbide blades. But you will need to use the right tools and know when to do the job.
Keep in mind that even the sharpest, most durable circular saw blades will dull over time and use. This includes carbide-tipped blades that are designed to hold up for years. But when will you know that your circular saw blade needs sharpening?
Signs of a Dull Circular Saw Blade
The two main signs start with the cuts themselves not being quite as sharp. It may be subtle at first, but the cuts into the material will not quite have the straight, clean lines that you have seen before from your circular saw. It is a good idea to take a photo or two when you first get your circular saw blade and then compare the image to how the blade cuts with materials right now. Pay special attention to the cut edges for burr and surface quality. The difference should be enough to see.
The second sign is the motor working harder as the material is being cut through. Again, it may be a subtle difference, but you’ll hear the motor pitching a little higher as it works harder to cut through. Over time, the harder the motor must work, the more likely it will break down. You may also smell the burning of oil inside the motor which is another sign it is working harder.
You may also notice that the sound the blade produce during cutting is also different. Dull blades will have hard time penetrating into the material and as a result more friction and heat is generated.
Cost of Sharpening Circular Saw Blades
You can either sharpen the blade yourself or have a professional do it for you. Although the cost will vary depending on the quality, size, and material of the blade, you can expect to pay from 25 to 50 cents for every tooth of the blade that is sharpened. The result will be a circular saw blade in almost new condition and the sharpening should last for about as long depending on its use.
However, circular saw blades that are carbide-tipped might be more expensive since it requires special sharpening tools.
Also, if the blade is cheap, then it probably isn’t worth sharpening at all. Normally I do not bother re-sharpening blades that costs less than $50. On the other hand, blades more than $100+ are definitely going to a grinding shop.
If you acquire lower-quality blades, then you should pitch them out as soon as they stop making clean cuts. Or, you can save them for use in demolition, remodeling, or wood that may have nails or other hard objects hidden inside that you do not want to risk your higher-quality blades to cut.
Sharpen the Blade Yourself
If you have the time and want to sharpen a circular saw blade by yourself, it can be done. However, this is not an easy task and if you have any real concerns, it is best to let a professional sharpen the blade for you.
Keep in mind that you need diamond wheels to sharpen carbide tipped blades. A dedicated tool and cutter grinder works is the best machine to sharpen the blades. But, if you want to do it yourself, then you need to have the right tools and techniques.
How to Sharpen a Circular Saw Blade by Hand?
Do not want to invest money in an electric sharpener or spend money on a sharpening service? You can do it by yourself with a diamond sharpener. However, result will vary depending on the blade condition and your experience.
Here is an excellent video that explains the sharpening process.
You could also use a die grinder or Dremel tool to recondition the blunt cutting edges.
If you are not confident, watch few more examples. YouTube is an excellent resource for lots of things, including how to sharpen a circular saw blade by yourself. Before reading the following instructions, it helps to visualize the process and there are some excellent how-to-sharpen videos available.
Sharpening wood blades by hand is a cost effective method that can produce decent results. However, for metal cutting circular saw blades, I strongly recommend you to get them ground.
Understand Failure
Keep in mind that if you do not sharpen the blade correctly, it may become useless. Worse, it may cause real damage to the material. So, be aware before you try to sharpen circular saw blades yourself.
Preparation
Cut a piece of wood at a 20-degree angle. Make sure that the angle cut is long enough to comfortable hold your diamond file or sharpening stick.
Execution
Lay the sharpening stick flat against the wood. Then place the wood on the circular saw table, so that the sharpening stick fits into the gullet between the teeth of the saw. Press the tooth of the saw into the sharpening stick.
Now, move the sharpening stick back and forth across the blade of the tooth. You can add a little oil to lubricate the stick and make the sharpening process go faster.
You do not need to sharpen long on each tooth, but it will take you an average of 10 minutes to sharpen all the teeth in this manner. Be sure that you are sharpening by going straight across or perpendicular to the tooth and not at an angle.
Clean-Up
Be sure to clean off the sharpening stick after each use. Keep in mind that sharpening sticks are rather inexpensive, and they tend to wear out quickly. Therefore, it is best to purchase them in packs so they can be quickly disposed of after each use.
If you decide on sharpening the blade yourself, be sure to follow each step and perform the work precisely to avoid any issues.
Dan Miller is a professional toolmaker with extensive experience in the metalworking and tooling industry.
An avid DIY enthusiast and passionate hobbyist woodworker, Dan shares his expert knowledge here.