Circular Saw Blade
A circular saw can reliably cut wood, metal, plastic, and even building materials like concrete or natural stone. The cutting work is performed by the circular saw blade. Since there are different types of circular saw blades, some basic knowledge is helpful. This guide reveals everything about the right circular saw blade.
What is a circular saw blade
A circular saw blade is a rotating tool used for cutting, employed in stationary or handheld circular saws. Regardless of their specialization, all circular saw blades share some common properties:
- round basic shape
- cutting teeth around the circumference
- suitable for cutting various materials
However, the base material, the number of saw teeth, and the intended use can vary.
Generally speaking, there are two types of circular saw blades that differ in their manufacturing and structure:
- Single-piece saw blades: stamped from a base material and equipped with the desired tooth shape
- Composite circular saw blades: consisting of a metal core onto which cutting edges (teeth) made of other materials are soldered
Short longitudinal and cross cuts in hardwood as well as high cutting quality in softwood are easily achievable with single-piece circular saw blades. Composite circular saw blades, on the other hand, are better suited for hardwood and harder composite materials. This is due to their staggered (alternately arranged) tooth row, which is wider than the metal core of the blade and runs with less friction through hard materials.
There are three tooth positions for circular saw blades:
- negative
- neutral
- positive
It's all about the tooth position
With the negative position, the separation angle in the material is very shallow, requiring a lot of feed force. This type is mainly intended for cutting hard metals like stainless steel.
With neutral tooth position, there is no rake angle to the central axis, and the entire tooth edge is loaded. This also requires high feed force, but the tooth edge behaves very robustly when hitting the material. Circular saw blades with neutral position are suitable for various metals and light metals.
The positive tooth position is typical for sawing wood. The teeth literally bite into the material and thus perform feed work independently. However, the tips are heavily loaded, so foreign objects like nails or screws can quickly damage the teeth.
Finding the right circular saw blade
Four properties play a crucial role in selecting the appropriate circular saw blade. Regarding the teeth, it is their number and type, and the cutting width and the blade's speed are also important.
Number of teeth
The more teeth a saw blade has, the finer the quality of the cut. Depending on the material to be cut, high tooth counts are not generally recommended. Similar to tooth position, there are three categories here:
- low: to 36 teeth, large chip gap, cutting performance is the focus, cut quality is coarse and rough, best for cuts along the grain
- high: between 36 and 48 teeth, cross cuts achieve clean results, saw blades quickly clog with longitudinal cuts
- very high: 60 or more teeth, very fine cut quality, used for thin materials, such as plywood, with slow cutting speed and more feed
In principle, at least three teeth should always be in the material during the cut to enable clean work. Therefore, the disc diameter should be chosen depending on the workpiece and its size.
Finding the right circular saw blade
Four properties play a crucial role in selecting the appropriate circular saw blade. Regarding the teeth, it is their number and type, and the cutting width and the blade's speed are also important.
For the cutting quality and durability of the circular saw blade, the type of teeth is decisive. The most common tooth shape is the rectangular flat tooth, which is ideal for longitudinal cuts in soft and hardwood.
Alternate teeth have a beveled back. They are often used as universal saw blades because they are suitable for both longitudinal and cross cuts.
Trapezoidal flat teeth are very robust and suitable for hard materials because they are particularly resistant to foreign objects.
Cutting width
The cutting width depends on the thickness of the saw blade and its teeth. The thinner the circular saw blade, the lower the speed should be set. At too high a speed and strong heating, there is an increased risk of accidents.
Speed
The cutting speed – that is, the speed at which the saw blade moves back and forth – should not exceed 100 meters per second. The larger the circular saw blade, the lower the speed should be set. The material being processed also dictates how high the speed should be set: non-ferrous metal (NE-metal) and plastic can be cut at up to 5,000 revolutions per minute, wood even up to 9,000.
How is a circular saw blade changed?
Basically, the saw blade must be fixed, the power supply interrupted, and the fastening screw loosened. Then replace the blade and tighten the screw again. Specific instructions can be found in the operating manual of the respective device.
What to do if the hole in the blade is too large?
The standard size has a diameter of 30 mm. If a blade of this size does not fit on the saw, so-called reducing rings can be used. These reduce the size of the hole and make the circular saw blade compatible with the power tool.
How to recognize dull circular saw blades?
Signs of dullness include slower sawing speed, discoloration due to overheating at the cutting edges, increased noise, and vibrations. Vibrations should be responded to immediately, as they are signs of an imbalance that can cause the circular saw blade to shatter. Dull saw blades do not necessarily need to be replaced; they can be resharpened up to ten times.
