Tap Guide
Styles | Chamfer
| Markings | Symbols | Thread Forms
Link to
Tap Recommendations for Class of thread | How to order Special Taps | Special Taps Dimensions Page |
Link to "everything you wanted to know about taps but were afraid to ask"
Tap Style GuideLink to Tap Recommendations for Class of thread | How to order Special Taps | Special Taps Dimensions Page |
Link to "everything you wanted to know about taps but were afraid to ask"
HAND TAP SPIRAL POINT TAP
SPIRAL FLUTED TAP INTERRUPTED THREAD TAP THREAD FORMING TAP
PIPE TAP COMBINED DRILL & TAP ACME THREAD TAP
TRAPEZOIDAL THREAD TAP ( these are the metric equivalent of Acme Taps but with a 30° included angle )
TANDEM ACME TAP EXTENSION TAPS (Incl. Nut & Pulley Taps)
EXTENSION TAP
PULLEY TAP
NUT TAP
SOLID CARBIDE TAP
CARBIDE INSERT TAP |

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Pitch Diameter Limit Symbols All standard ground thread taps are marked with the letter "G" to designate Ground Thread. The letter G will be followed by the letter "H" to designate above basic; or the letter "L" to designate below basic. The number following H or L signifies the number of .0005" steps above or below the basic pitch diameter. For instance, the tap pictured above is a 3/8" dia. tap with 20 threads per inch (pitch), and has a NS (American National Special Thread) thread form. The tap is made from High Speed Steel, and the GH-3 pitch diameter limit symbol indicates a Ground Thread tap with pitch diameter limits .0010 to .0015 over basic. Pitch Diameter Limits for taps to 1" diameter inclusive: L1 = Basic to Basic minus .0005 Taps larger than 1" dia. are ground to a .0010" tolerance on the pitch diameter and are, for example, H4 (Basic plus .0010" to Basic plus .0020"). |
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*Taps are not marked with "U" but with the symbol for the corresponding American Standard thread form with which it is compatible. |