Straight Flute Tap
Widely used for general hand and machine tapping operations. Available in sizes thru 1-1/2".

Plug Style - (4 Thread Chamfer).
Used in thru holes and blind holes that allow for ample chip clear ance. Easier to start and require less tapping torque than bottoming taps.
Unit of Measure


On Hand

N/A {0}

Thread Size

N/A 5/16-18


N/A Plug

Thread Size Inch

N/A .312 in

Class of Fit

N/A 3B

A - Length Overall

N/A 2.938 in a1357.jpg

B - Thread Length

N/A 1.250 in

C - Length of Square

N/A .438 in

D - Max. Shank Diameter

N/A .381 in

Max. Size of Square

N/A .286 in

Number of Flutes

N/A 4

Tap Style

N/A 2

H - Limits

N/A H3

N/A Special STI Taps
Taps made to different limits, configurations, or to cut difficult materials, or for very high production are available upon request. The following data should be provided at the time of ordering:

  • Thread size
  • Class of fit. Example: 3B, 2B, Special Size to Special Tolerance.
  • Material to be cut, and its hardness.
  • Hole configuration. Example: Thru or Blind including length of drilled and tapped hole.
  • Type tap. Example: Plug or Bottoming Straight Flute, Spiral Point, Spiral Flute.
  • Special features. Example: Length, Shank Diameter, Chamfer Length, Tap Material.
  • Special coating of tap.