Tap Drill Size for NPT & NPTF Taper Threads
Tap Drill Size for NPT and NPTF Taper Threads

You got the job. You ordered and received material. You ordered and received taps and gages from North American Tool. The job is now out in the shop to be manufactured and the first operation is to produce a hole before tapping. How do you determine what tooling to do that with?
Holes before tapping pipe threads are produced either straight or tapered. The choice of method is
National Pipe Taper vs. National Pipe Taper Fuel
Ever wonder what the difference is between an NPT (National Pipe Taper) and NPTF (National Pipe Taper Fuel) threads are? It’s not just the spelling.
They are both the same in many ways,
- both are used to carry fluids and gasses
- both have the same diameter, thread per inch combination, sizes, 1/16-27, 1/8-27, ¼-18, etc.
- both have an included thread angle of 60 degrees.
- both have a thread that tapers 3/4 per inch per foot or 1/16 per inch.
- both have flatted crest and roots
- both have the same pitch
GWS Tool Group Announces Acquisition of North American Tool Corporation
The acquisition of North American Tool Corporation extends custom product capability into the threading space, a new offering for GWS that adds a powerful dimension to the already robust product and service portfolio.
Tavares, FL February 4th, 2020 – GWS Tool Group is pleased to announce it has acquired North American Tool Corporation (NATC). They represent the second add-on acquisition in 2020 for GWS.
Located in Northern Illinois, North American Tool is a world-class supplier of special taps, dies, and gages. From solid carbide thread mills to high-speed steel taps and thread gages, North American Tool delivers high-quality specialized threading
North American Tool Corporation Appoints Steve Mayse as Director of Manufacturing
North American Tool Corporation, South Beloit, IL, has announced the appointment of Steve Mayse as Director of Manufacturing.
Mayse will be responsible for developing and implementing operational strategies to strengthen and grow the manufacturing performance at North American Tool Corporation, a leading provider of special taps, thread mills, dies and gages to industrial markets, and Allen Benjamin Inc., a manufacturer of carbide and premium HSSE taps.
Steve brings a wealth of relevant manufacturing experience to his new position, with more than 35 years of senior management expertise, implementing strategic development and growth execution plans at various leading-edge manufacturers.
“Steve
How Do You Spell Relief?
Have you ever had a tapping job that was so troublesome that it caused heartburn or acid indigestion due to broken taps, bad finish, short tap life, over or undersized threads, ETC.?
One way of avoiding or alleviating such a condition is accomplished with the use of a tap feature called “relief”. The definition of “relief” according to Marian Webster, is removal or lightening of something oppressive, painful, or distressing. For a tap, “relief” is the reducing of surface contact between the tap/tap feature and the part being tapped. Surface contact generates unwanted heat causing the
Controlled Root Tap
First things first, what is the root of a tap?
The root of a tap is the surface at the bottom of the thread-form that connects adjacent thread flanks and is expressed as width or as a diameter. The term root diameter is also called minor diameter, it’s one of those things, you say rain and I say precipitation, meaning the same thing.

The root of a tap, unless designed as a controlled root tap, normally does nothing, it is a
CALCULATING “BEFORE PLATE” INTERNAL SCREW THREAD AND TAP “H” LIMITS
We realize how confusing the painstaking math is to get preplate part limits and a Tap “H” limit, but don’t worry, all you have to do is contact us with your thread information, and we will do the work. Call us at 800-USA-TAPS.
If you want to know how it's done, we’ve included the formulas for the engineer in all of us.
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