You can do the same 'simple subtraction' with Imperial 60° threads by first converting OD and pitch to metric. In theory the tapping hole is 95%, but in practice a screw thread is under-size and drill will drill sufficiently oversize to just use the 100% number. If you are asking this about a metric series thread - subtract the thread pitch from the screw OD. Thread geometry - British Standard Whitworth (BSW) All dimensions in inches unless otherwise stated.

If we multiply this factor times the total length of seam, we can determine the total thread consumed for that seam. Convert 2.54 cm to millimeters by multiplying that value by 10. By dividing the amount of thread by the seam length, we get the ratio of thread consumed. Also, you can calculate as follows: Remember that 1 inch is 2.54 cm. All units shall be consistant and given in inches. IF the question means 'how do you decide the tapping hole diameter' this varies with the thread system - so look it up in a book or chart. 25.4mm You can check our metric to inches calculator and seek for inch definition. Fastener / Thread Pitch Circle Calculator - This calculator will determine. That number of threads required times the pitch gives the depth required. If you need to know the threads per inch of a metric fastener, first convert pitch from millimeters to inches (multiply by 0.03937), then divide 1 by that. When you divide this thread effective area into the area the material said you need to equal the screws root strength, you get how many threads are required. The effective area of the thread is roughly 80% of thread OD less root dia. To work out the 'holding strength' exactly you need the tensile strength of the threads root diameter (root area x tensile of the screws material) compared to the effective area of the thread engaged in the base material times that materials compressive strength. But as this 1.5 or 2.5 decision is based in a feeling for the materials, allow me to add To use this online calculator for Pitch Diameter of External Thread given Pitch, enter Major Diameter of External Thread (d) & Pitch of threads (p) and hit the calculate button.

Threads per inch calculator