The TPI and PPI Saw Measuring Systems
In the United States, the teeth are counted beginning at the gullet’s bottom. Whole numbers are used in the counting. If the end is a point, the counting is a whole number with ½. The system of counting is called teeth per inch or TPI.
European saws are counted from the point only, never the gullet. The points are counted within the inch. This system is called point per inch, or PPI.
The TPI is indicative of both saw size and usage. A 2 to 3 refers to the logger’s saws. This is used for cutting green wood along the grain. The 41/2 rip saw is used for slicing wood across grain. The TPI 9 refers to pruning saws and the 9-20 TPI are crosscut saws. This is also used for cutting wood.
Measuring Circular Saw Blades
Circular saw blades are counted by the number of teeth present. In the United States, the circular saw blades are created by inch diameters. The sizes used are 4, 4 3/8, 5½, 6½, 7, 7¼ and 7½. 8, 8¼, 9, 10, and 12 are sold to consumers.
Except for the 12 inch blades, all the sizes fit a 5/8 inch arbor. The 12 inch saw size possesses a 1 inch center blade. Among portable saws, the 7¼ inch is the most common. Among radial and table saws, the 10” is the most widely used.
Scroll saw blades are either flat or pin end. Most saws can use both. The length is usually 5 inches (130 mm). The blades are sold according to numbers, from 0 to 12. The higher the number, the less teeth are present. The biggest is the ¾ inch. The smaller ones are used for cutting veneer. The thicker ones are used for slicing stock.
Most hacksaw blades are a foot long (12 inches). There are also 10 inch saw sizes available. Most hacksaw frames are also adjustable; they can accommodate blades from 8 to 12 inches long. The blade is linked to the frame via small holes. These are then fitted over the pins.
There are also larger hacksaws available. These can handle 30 inch blades. A junior hacksaw can take in a 6 inch blade. The blades are usually constructed 14 to 32 teeth for every inch.
Jeweler’s Saw Blades
These are usually 4 inches long and designed for slicing metal. Size 8/0 is equal to 84 TPI; 5/0 is the same as 76 and 3/0, 64. The 0 size is equivalent to 56 TPI. Other sizes are (1, 47 TPI; 2, 44; 3, 40; 4, 37; 5, 35; 6, 33 and 7, 30 TPI.
For new users, familiarity with saw sizes is an essential step to learning how to use the device. How effectively you can cut the material depends on the saw.