Sharpening a circular saw blade - Why it matters
Anyone that has spent time woodworking can tell you that sharpening a circular saw blade is the key to maximizing precisions and cutting performance on any project. When properly sharpened, the right circular saw blade can cut through almost any material – wood, concrete, metal, etc. However, as with other woodworking tools, a circular saw blade will wear down and become dull when used frequently, which can seriously impede the efficacy of your cutting. A dull saw blade will cut slower, create more tears and chipping, and can cause more wood burn leading to an unsafe work environment. Therefore, it is crucial to keep your circular saw blade sharp and prepped for use.
Types of Saw Blades
Before looking at how to sharpen your circular saw blades, let’s first take a look at the different types of blades that are currently available on the market. Depending on your type of circular saw and the type of blade it has, the steps you’ll take to sharpen that blade may vary.
- Carbide-tipped: This is the most common type of circular saw blade. This type of saw blade is made of a steel disc with carbide-tipped cutting teeth around the outside edge of the blade. These types of blades are primarily used for cutting wood, and their shelf lives depend on the tooth count and the types of material they’re used to cut.
- Steel-tipped: These types of blades used to be the most common types of circular saw blades on the market before carbide-tipped blades became readily available for woodworkers. These blades are 100% steel and only last about 10% as long as carbide-tipped blades.
- Diamond-edged: These blades are most commonly used among professional and novice masons and are designed to cut materials like concrete, tile, and brick. These blades typically do not have any teeth; They are entirely circular. The outer perimeter of these saws is covered in diamonds.
Is it time to consider sharpening my circular saw blade?
All circular saw blades will dull over time regardless of the type and material that they are made of.
Some of the early signs of dulling in carbide-tipped and steel-tipped blades are:
- Slow-cutting or binding mid-cut
- More frequent tearing or chipping
- Producing burn marks and smoking when cutting wood
Some of the early signs of dulling in diamond-edged blades are:
- A glazing over of the blade, which indicates that the metal bonding holding the diamonds on the blade has melted
- Slow-cutting or binding mid-cut
- A smooth-looking blade, indicating the diamonds have worn off
More experienced woodworkers and masons will develop a feel for their circular saw blade wearing. As you work more regularly with these tools, you will notice that you have to simply push harder to get your materials cut, which is usually one of the first signs that your blade needs to be sharpened.
Other tell-tale signs that develop later than the signs mentioned above include missing circular saw blade teeth, a degraded cut quality on your materials, and a laboring sound when wood is being cut.
Sharpening circular saw blades
When your blades show signs of needing to be sharpened, you face a choice – should you replace your saw blades or should you sharpen them? Generally speaking, if you have spent $50 or more on the blades, it is worth sharpening your circular saw blade instead of buying a new one. Sharpening your circular saw blades will reduce waste and save you money long-term, especially if you have invested in more expensive blades, like carbide-tipped ones.
There are a few options when it comes to sharpening your circular saw blades – you can either do the sharpening yourself or hire a professional.
Sharpening a circular saw blade yourself
The first thing to know about sharpening a circular saw blade on your own is that you need to have the right tools to do it. There are special grinding devices and machines that can be used for sharpening circular saw blades, but those tend to be more expensive than the tools that can be used to sharpen your circular blade by hand.
Selecting a circular saw blade sharpening machine
Having a circular saw blade sharpener will provide you with the following advantages:
- Accurate grind angle
- Faster sharpening time
- Ability to quickly sharpen more than one blade
- Money-saver over time
Keep the following tips in mind when looking to buy a circular saw blade sharpening machine:
- Motor block tilt: the sharpening machine will need to tilt in order to be at the proper angle to sharpen the saw blade teeth, so be wary of any machine with less than a 25-degree tilt angle.
- Saw blade size: circular saw blades vary in size, generally ranging from 6.5in-12in, with some blades as large as 16in. Make sure to select a machine that can handle the size of your circular saw blade.
- Saw blade support: your circular saw blade will need to be attached to the sharpening tool using a tightening screw. Consider selecting a machine with added rigidity because it will keep the blade in position as the grinding wheel moves across the teeth of the blade while sharpening.
- Disk materials: grinding and polishing disks come in either a diamond or an emory surface. Diamond wheels are required for carbide-tipped circular saw blades and are intended for course material removal. Emory wheels provide a finer edge to the saw blade teeth and are designed for use on steel-tipped blades.
Sharpening a circular saw blade by hand
If you do not wish to invest in a circular saw blade sharpening machine, you have the option of sharpening your circular saw blade by hand. Keep in mind that this method cannot be used for a carbide-tipped saw blade.
The tools you will need to sharpen your circular saw blade by hand are:
- A ring spanner
- A triangular file
- A flat file
- 2 screw clamps
Follow these steps to sharpen your circular saw blade:
Step 1: Remove the saw blade
First, remove the circular saw blade from the saw by loosening the nut by turning it clockwise using a ring spanner and safely detaching the blade from the saw.
Step 2: Clean the blade
Properly cleaning your circular saw blade will make it easier to sharpen and will reduce any potential damage from being done to your blade.
Step 3: Fix the saw blade to the workbench for sharpening
Use the two screw clamps to clamp the blade tightly to your workbench so that there is as little vibration as possible while sharpening.
Step 4: Make a mark
Make an identifying mark on the side of the blade so that you will know when you have sharpened all the way around the circular blade. Follow these steps to complete the marking process:
- Tilt your file around 20-degrees.
- Fill 4-5 times up and down along the bevel. If you still don’t see any markings, repeat your filing a few more times.
- Bevels appear on every other tooth of the circular saw blade, so you can mark every 2nd tooth. Follow this pattern to keep marking the edge until you reach the end.
Step 5: Trim the saw teeth
It is necessary to trim the teeth of the saw blade before sharpening whenever the teeth have become uneven due to frequent use.
Using the flat file tool, file the tips of the teeth so that they are the same height. Use repeated horizontal file strokes over the rows of the circular saw blade teeth.
Please note that it may be necessary to reset some of the teeth of the saw blade by bending them so that they are in line with all of the other teeth. This prevents your project materials from getting stuck whenever you are attempting to make a cut. If you notice that any of the circular saw blade teeth need to be reset, do so during this step using pliers.
Step 6: Sharpening
Once your saw blade teeth have been filed and set, it is time to sharpen them using the triangular file. Run the file from back to front on each circular saw blade tooth. File each tooth’s top with the sharpener by following the same process so that your filing is done evenly and consistently across all of the blade’s teeth.
This should be done on both sides of the saw.
Step 7: Reinstall the newly-sharpened circular saw blade
Correctly reinstall the newly-sharpened circular saw blade into the saw. Take care to reinstall the blade correctly with a tight fit in order to avoid an imbalanced blade. Using the ring spanner, tighten the nuts by turning them counterclockwise.
Step 8: Test your resharpened blade
Double-check your sharpening and your blade reattachment by sawing a scrap piece of wood.
The following signs indicate that you have successfully sharpened your saw blade:
- Your cutting will run smoothly with hardly any additional noise
- Your cutting will be even and won’t require any additional effort exertion