The1/16”, 1/8”, 1/4”, and 3/8” sizes have a dissimilar pitch, which causes a misalignment of the threads. The flank angles of the threads are also different between NPT and BSP. NPT has a 60° thread where the BSP has a 55° thread. Figure 5 shows a WhatSize Drill Bit for 1/4” NPT Tap? A ¼” NPT Tap needs a drill bit size of 7/16 inches or 0.4375 inches in decimals. NPT taps are commonly called pipe taps by most people. Don’t confuse them with NPTF taps and tapered taps like the 8-32 tap as they are used for different purposes. Thispage provided the thread dimensions of 1 1/4 - 11 1/2 NPTF. NPTF stands for National Pipe Thread Fuel, based on ASTM B1.20.3. It is also called Dryseal Pipe Thread. It is a variation of the more popular NPT thread standard based on ASTM B1.20.1. Learn more about NPTF and the difference between NPTF and NPT. Whilestandard screw threads generally use between 10 and 12.5 percent truncation, the pipe threads seem to use a smaller percentage. The 1/16 - 27 NPT in particular uses between 0.0012" (minimum) and 0.0036" (maximum) truncation at both areas. That translates to percentages between 3.74% and 11.2%. I have found that using a 1¼” NPT taps need a 1 1/2 inches size drill bit and can be used for re-threading damaged pipe threads. They’re mostly used for tapping fittings and couplings much like the 1/8″ Diameter The diameters are given in inch fractions. For example, 1/4″, 3/4″, 1 1/4″. It is also allowed to denote the diameters with a decimal value. For example, 0.250 (1/4″), 0.4375 2031. 2-1/16. 2.062. 3-1/8. 2.180. 1. Countersink. It is considered good practice to countersink or break the edges of holes that are smaller than F (max.) in parts having a hardness which approaches, equals, or exceeds the screw hardness. If such holes are not countersunk, the heads of screws may not seat properly or the sharp edges on holes BSPTRc 1/8 : Brith Pipe (BSP) Thread Dimensions and Tolerances. All the relevant data for this tread in one spot. Dryseal Pipe Threads (NPTF) British Pipe Threads (BSP) ACME Trapezoidal Threads; Minimum length of useful threads (L min) 4.5 : 0.1772 : Tap Drill Size (T d) 8.4 : 0.3307 : Browse Ads-Free For Just 1.5$ / Month. Login Theformulas for metric internal thread dimensions; and; Typically, metric thread callouts also come with the thread pitch, such that an M6 × 1 threaded bolt has a basic major diameter of 6 mm and a thread pitch of 1 mm. When purchasing a threaded fastener, make sure you have both the diameter and the thread pitch. PEqEov9.

1 4 npt thread drill size