What is blade TPI? How do you select the best TPI for your project? It is easy to become overwhelmed with all the saw blade choices on the market when trying to decide on the proper blade for your tool. There are a number of factors that should be taken into consideration including the TPI, what type of saw you are using, what you’ll be cutting, and what type of cut you want. Let’s begin with a little bit of background on what TPI actually is.
What is TPI?
TPI is simply the teeth per inch. The TPI of a saw blade can be calculated by measuring out one inch on the saw blade starting from the center of a gullet, and counting the number of teeth. A saw blade that has more TPI (and less gullets) will have a slower cut, but a clean and smooth finish. A saw blade with a lower TPI (and large gullets) will cut much faster, but the finish will be rougher. There are 3 general categories that saw blades are divided into based on their TPI. They are coarse-toothed blades, medium-toothed blades, and fine-toothed blades.
Coarse-toothed blades have 1-7 TPI and typically have large teeth and deep gullets. Large teeth and deeper gullets cut a larger quantity of material away with each stroke of the saw, and as a result cut much quicker than blades with more TPI. The aggressive cutting action of coarse-toothed saw blades create a rough finish.
Due to the low TPI and aggressive quick cutting, coarse-toothed saw blades are ideal in situations where a neat finish is not important. A band saw is an example of a coarse-toothed saw and typically has a TPI between 3 and 8. Band saws are typically used for cutting tree branches and rough cutting logs.
Medium-toothed blades have 7-10 TPI and have smaller teeth and shallower gullets than the coarse-toothed blades. The smaller teeth and shallower gullets result in less material being cut away with each stroke of the saw blade. The cut is slower and cleaner than that of the coarse-toothed saw blade. These blades are mostly found on saws used for general purpose cutting.
Fine-toothed blades have 10 or more TPI and small teeth and shallow gullets. With each stroke of the saw, the least amount of material is being cut away. Fine-toothed blades cut the slowest and have the least aggressive cut of all blade types. With a less aggressive cut, fine-toothed saw blades result in a neat and smooth finish. A coping saw is one example of a saw with a fine-toothed blade. Coping saws are ideal for slow, controlled, and precise cutting that requires a smooth and neat finish.
There are two general categories that saw blades are divided into. They include straight blades like on reciprocating and jig saws, and circular blades like on table, miter, and circular saws. There are a number of other factors to consider before choosing a saw blade, and they depend on what type of saw you are using and what you are going to be cutting.
Choosing Table, Miter, and Circular Saw Blades
While the table, circular, and miter saw all have circular blades, they are different in the construction of the teeth. Circular saw blade designs are very similar to table saw blades with a few minor differences. The miter saw blade utilizes a circular blade but with differences in the design if the teeth.
Table saw blades are classified based on the shape, or grind, of their teeth. Most table saw blades come in a diameter of 10”.
There are four basic types, the blade you choose will depend on the type of cut you want.
- Flat top grind (FTG)
Flat top grind saw blades have teeth with top edges that are square to the saw plate, are fast cutting, and durable. These teeth are also called rakers. FTG saw blades are designed for ripping by sawing perpendicular to the grain, and will produce a rough cut surface. 24-tooth FTG blades are a good choice when it comes to rough ripping of lumber, but if you want a cleaner cut a 40- or 50-toothed blade will do the trick.
- Alternate top bevel (ATB)
Alternate top bevel blades are angled across the top edge, with every other tooth angled in the opposite direction. This blade works by shearing the wood fibers in a slicing motion, which makes them ideal for crosscutting. As a general rule of thumb, the steeper the bevel angle is, the cleaner the cut will be. But the teeth will also dull faster.
- Combination (ATBR)
Combination blades have 50 teeth that are arranged in sets of 5 with four alternate top bevel teeth followed by a raker tooth. The first five teeth are designed to crosscut cleanly while the raker teeth aid in the ripping. ATBR blades are also marketed as all-purpose blades and are a good choice for cross cutting job.
- Triple-chip grind (TCG)
Triple-chip grind saw blades have teeth that alternate between a raker tooth and a chamfered tooth. The chamfered tooth roughly makes the cut and the raker tooth cleans it up. The TCG saw blades are designed for sawing dense materials such as solid surface materials like Corian, plastic laminates, and non-ferrous metals.
Best FTG Saw Blade
Freud 10" 24 Tooth Ripping Saw Blade
The heavy duty ripping blade from Freud makes quick work of lumber due to the thin kerf and positive hook angle. Features laser cut anti-vibration vents for extended blade life. Works best with material between 3/4" and 2-3/4" thick. Non-stick perma-shield coating gives extra protection against corrosion and pitch build-up.
Most ATB blades have 40 teeth, are marketed as all-purpose blades and are best used on cutting plywood. While 40-toothed ATB blades can be used just fine for crosscutting, 80- or 100-toothed blades will give a much cleaner cut.
Best ATB Saw Blade
Freud D1080X Diablo 10" 80-tooth ATB
Another excellent table saw blade from Freud. The D1080X Diablo 10" 80-tooth ATB blade is manfucatured in Italy and provides excellent finish cutting performance. The laser cut stabilizer vents trap noise and vibration, reducing blade warpage. This blade is a great choice for cutting fine molding and stock used in cabinets and furniture.
Best Combination Saw Blade
CMT 215.050.10 Industrial Combination Blade
The CMT 215 Industrial Combination Blade is an excellent choice for ripping and crosscuts. The large gullets allow deep cuts with great chip clearance. Micrograin carbide teeth laser longer while delivering smoother than expected cuts. The non-stick PTFE coating keeps the blade cool and reduces corrosion, extending blade life.
Best TCG Saw Blade
The Freud LM740M010 30-tooth Glue Line Ripping saw blade provides long life and great finish cutting. The Silver ICE coating resists corrosion and resin build-up while also providing 2 times more heat resistance than polished blades. The triple chip tooth produces a finish suitable for gluing and other finish work. No need to sand after your cut!
The circular saw is a type of hand saw that utilizes circular blades similar to those of the table saw. They are most commonly found in 8”, 10”, and 12” diameters, but can also be found in diameters ranging from 5 ½” to 24”. The diameter of the blade will determine the depth of the cut. Circular saw blades are typically tungsten carbide tipped for precision and longevity due to the nature of their use, but high-speed steel blades can also be found.
Circular saw blades have a straight, narrow, and accurate cut with a relatively smooth surface. The design of the blade needed can be determined by whether you are performing general lumber cutting such as ripping and crosscutting, and whether you are cutting plywood, plastic laminates, particle board, hardboard, or medium-density fiberboard. The same blade types discussed above for table saw also apply to circular saws.
A miter saw operates by manually pulling the saw blade down onto the material that is being cut. This material is held firmly against a “fence”, which ensures a precise and accurate cut. The main difference between the blades of a miter saw and those of a table saw or circular saw is the angle of the teeth.
The teeth of a miter saw have a negative hook at the end that holds the material against the fence, whereas a table saw and circular saw have a hook that pulls the material towards the blade. Miter saws are most commonly used in creating frames and cutting moldings. They are created for crosscutting and are not suitable for long rips.
There are four basic cuts for the miter saw:
- A miter cut that is angled across the width of the board
- A compound cut combining miter and beveled cuts
- A beveled cut which cuts part-way into the thickness of the board
- A straight cut across the grain of the board
Choosing Reciprocating Saw Blades
A reciprocating saw applies to any saw that has an oscillating back and forth cutting motion. These include jigsaws, scroll saws, sabre saws, and rotary reciprocating saws. When choosing a reciprocating saw blade there are two main things take into consideration.
There are three main types of reciprocating blades and each has its own purpose:
What will you be cutting?
- High-speed steel blades are ideal for cutting non-ferrous metals such as aluminum, copper, and brass.
- High Carbon steel blades are designed for softer material such as wood, particleboard, plastics, and laminates.
- Bi-metal blades are combination of high-speed steel and high-carbon steel. This results in a tough and flexible blade that is suitable for the most demanding of applications where versatility and breakage are factors.
How dense is the material?
To achieve the best cut, it is important to match the density of the material you are cutting with the proper TPI. For dense material you want more TPI, and for less dense materials you want less TPI. Cutting material that is too dense for the TPI of your blade will quickly result in a dull and useless blade.
Every woodworking shop or hobbyist should have at least three, maybe even four different blades handy:
- A good quality general purpose or combination blade that will be used for 90% of your sawing tasks.
- A blade for cutting hard woods such as a 24-toothed rip blade. This saw blade will also save wear and tear on your everyday general purpose or combination blade.
- A premium 40-toothed all-purpose blade dedicated to crosscutting lumber and most plywood. If funds are not an issue, an 80-toothed blade will make the best cross-cuts and panel cuts possible.
- A TCG blade if you work with a lot of laminates and non-ferrous metals. Most other blade will just dull of used on these materials, which in the long run costs more money.
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