# How are Whitworth threads measured?

## How are Whitworth threads measured?

The form of a Whitworth thread is based on a fundamental triangle with an angle of 55° at each peak and valley. The sides are at a flank angle of Θ = 27.5° perpendicular to the axis. Thus, if the thread pitch is p, the height of the fundamental triangle is H = p/(2tanΘ) = 0.96049106p.

Are Whitworth and UNC threads the same?

Whitworth threads can really upset the apple cart. They often have the same TPI as UNC threads (see thread tables), but use a different thread angle of 55 degrees, whereas UNC and UNF use 60 degrees.

### Is British Standard and Whitworth the same?

British Standard Brass (for which there is no British Standard) is based upon the Whitworth thread form with all diameters having 26 threads per inch (tpi). It was used on general brass work, gas fittings and brass tubing. It is also reported that antenna bases should use this thread.

What is Whitworth size?

A Whitworth wrench is sized according to the diameter of the shank of the bolt, not the head. A 1/4 W (Whitworth) wrench is actually a bit larger than a 1/2″ American wrench—0.525″ to 0.500″. As if that wasn’t enough, in 1924 it was decided that the heads of the Whitworth bolts were too large, so they were down-sized.

#### What does Whitworth stand for?

English: habitational name from any of several places named Whitworth, from the Old English byname Hwita meaning ‘white’ (or the adjective hwit ‘white’) + Old English worð ‘enclosure’.

What is meant by Whitworth thread?

Definition of whitworth thread : a screw thread with V-shaped cut used chiefly in Britain for screws of larger sizes.

## Is G thread BSPP or BSPT?

BSP distinguishes between two types of threads. These are parallel threads (BSPP), which have a constant diameter, which are known a G threads, and taper threads (BSPT), whose diameter increases or decreases along the length of the thread, known as R threads.

What size is G1?

This is the source of the confusion, as people think the size refers to the outside diameter of the male thread. Two types of threads are used: Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP). These are sometimes denoted by the letter G, for example G1/2″ means a parallel 1/2 inch BSP thread.

### What is the pitch of a Whitworth thread?

Whitworth’s new standard specified a 55° thread angle and a thread depth of 0.640327p and a radius of 0.137329p. Where p is the pitch. The thread pitch increases with the diameter in steps specified on a chart. The Whitworth thread system was later to be adopted as a British Standard to become British Standard Whitworth (BSW).

What is the difference between BSW and Whitworth threads?

An example of the use of the Whitworth thread are the Royal Navy’s Crimean War gunboats. The British Standard Fine (BSF) standard has the same thread angle as the BSW, but has a finer thread pitch and smaller thread depth. This is more like the modern “mechanical” screw and was used for fine machinery and for steel bolts.

#### What happened to Whitworth threads?

The death knell for Whitworth threads was rung during WWII when it became apparent that a common thread system was desperately required for the Allies. Of course, this did not include the Russian who were dubious “Allies” at best. The British chose to embrace the U.S. SAE thread system but this transition took many years to complete.

Why are there two sizes of threads?

The reason for the two sizes goes back to the Industrial Revolution — to be exact the year 1841 because in that year Joseph Whitworth introduced the first standard thread to avoid confusion in Britain’s burgeoning engineering industry. The name of the thread was understandably eponymous, although its full name was British Standard Whitworth.