A general guide to TPI
TPI is an acronym for Teeth Per Inch and is a common measurement to be detailed on saws.
As a general rule, the more teeth per inch a saw has, the neater the finish will be, but the slower the saw will cut.
The fewer teeth per inch, the faster the saw will cut but the rougher the finish will be.
Blades with 1 to 7 TPI (Coarse-Toothed Blades)
Generally speaking, the fewer teeth per inch on a blade, the larger those teeth tend to be, and the deeper the gullets. This means that with each stroke of the saw, a larger quantity of material is being cut and removed.
As a result, a blade with fewer, larger teeth per inch will cut much quicker than one with more teeth. However, because of this aggressive cutting action, there is a greater chance that the material’s fibres will become torn, creating a rough finish.
A bow saw is an example of a saw which tends to have a low TPI. Bow saw blades usually have between 3 and 8 teeth per inch and are used for quickly cutting tree branches or roughly sawing logs to size.
Because they have fewer teeth per inch, they’re ideal for aggressive cutting where a neat finish is not important.
Blades with 1 to 10 TPI (Medium-Toothed Blades)
Generally, saw blades that have between 7 and 10 teeth per inch are often referred to as ‘medium-toothed’ blades. These types of blades are usually found on hand saws for wood or general-purpose cutting.
Blades with a medium TPI provide a balance between fast aggressive cutting, and slow, precise cutting. They can create a relatively neat finish if used correctly and yet will cut fairly quickly through the material.
Blades with 10 or more TPI (Fine-Toothed Blades)
Generally speaking, the more teeth per inch, the smaller the teeth tend to be and the shallower the gullets. This means that with each stroke of the saw, much less material is being cut and removed.
As a result, a blade with more teeth per inch will cut less quickly than one with fewer teeth per inch.
However, this less aggressive cutting style means that blades with more teeth per inch are less likely to tear the material’s fibres or cut away too much material at one time. So they therefore produce a neater finish.
A coping saw is a good example of a saw with more teeth per inch. Coping saws can have up to 32 TPI, making them ideal for slow yet very precise cutting when a neat finish and a controlled cut is more important than fast sawing.
Wonkee Donkee Tip
If you get stuck, just remember:
More teeth per inch = A neater finish but slower cut
Fewer teeth per inch = A rougher finish but faster cut