If you’re looking to tap a 1/8 NPT thread, you’ll need a drill bit that’s just slightly larger than 1/8″. In this blog post, we’ll show you what size drill bit you need for a 1/8 NPT tap, as well as offer some tips on how to drill the perfect hole.
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Introduction
NPT taps are used to create threads in pipes and fittings so that they can be connected together. The size of the drill bit you need to use for a 1/8 NPT tap depends on the threading method you will be using.
If you will be using a hand tap, you will need to use a drill bit that is slightly smaller than the tap. For example, a 1/8 NPT tap will require a #7 drill bit.
If you will be using a machine tap, you will need to use a drill bit that is slightly larger than the tap. For example, a 1/8 NPT tap will require a #6 drill bit.
Drill Bit Sizes for Taps
The correct drill bit size for a 1/8 NPT tap is #7. You can also use a #6 or 1/4″ drill bit, but these are slightly larger than necessary and may cause the tap to break.
Drill Bit Size for a 1/8 NPT Tap
To tap 1/8 NPT, you will need a #7 drill bit, which is 0.201 inches in diameter.
Drill Bit Size for a 1/4 NPT Tap
The specific drill bit size needed for a 1/4 NPT tap depends on the thread pitch of the tap. For a standard 1/4 NPT tap, you will need a #7 drill bit. If you’re not sure of the thread pitch, you can measure it with a thread pitch gauge.
Drill Bit Size for a 3/8 NPT Tap
The size of the drill bit you will need to use for a 3/8 NPT tap depends on the threading you will be using. For standard pipe threading, you will need to use a 1/2 inch drill bit.
Drill Bit Size for a 1/2 NPT Tap
The proper drill bit size for a 1/2 NPT tap is 29/64″. The tapping drill size is determined by the formula: (tap drill size = major diameter – pitch). The “major diameter” is the outside diameter of the thread (OD), while the “pitch” is the distance between adjacent threads measured parallel to the thread axis (which is equal to 1/thread pitch).
Conclusion
In order to properly tap 1/8 NPT threads, you will need to use a drill bit that is slightly smaller in diameter than the tap. The specific size needed will depend on the brand and type of tap being used. In general, a #7 drill bit should be used for taps up to and including 3/8″ in size. A #7-1/2 drill bit should be used for taps larger than 3/8″.
