"If you look at the front of the tooth you'll see two cutting surfaces separated by the carrier. The blade structure is like a sandwich." John Caron, global director of research and development for saws at Starrett.
The carrier strip wears when cutting begins, and the wear forms a small U-shaped groove between the two HSS edges. The groove is 0.001-inch to 0.002-inch deep and remains at a constant depth, wearing at the same rate as the teeth.
Starrett registered the name Split-Chip Advantage to describe the twin-tooth design, which produces two chips. "The two teeth break each chip into two pieces, and that is a significant benefit in reducing chips bonding to the saw teeth," Caron says.
Chips bonded to the teeth produce friction that increases as tooth temperature rises. Split chips tend to curl and fall away as strings instead of chunks, and they're less prone to cling to the teeth.
"Producing twice as many chips roughly half the size allows the blade to run cooler," Caron says. "Coolant flow carries the chips away faster, and the center groove forms a coolant passage that directs coolant into the tooth gullets."