Contents
- 1 What angle is a Whitworth thread?
- 2 Which type of thread has angle of 55 degree?
- 3 Are all threads 60 degrees?
- 4 What does BSF thread mean?
- 5 What is the most common thread angle?
- 6 When did Whitworth stop being used?
- 7 Is the British Association screw thread the same as the Whitworth standard?
- 8 Which is better British Standard or British Standard Whitworth?
- 9 Why did the British change the thread series?
What angle is a Whitworth thread?
55°
Thread form The form of a Whitworth thread is based on a fundamental triangle with an angle of 55° at each peak and valley.
Which type of thread has angle of 55 degree?
Whitworth threads
Thread angle
| Name | Code | Angle |
|---|---|---|
| Most V-threads (including ISO, NPT and UTS) | M | 60° |
| Whitworth threads | W | 55° |
| British standard pipe thread | G | 55° |
| National Pipe Thread | NPT | 60° |
Are all threads 60 degrees?
The angle of this “V” is called the thread angle, and is determined by fastener engineers. Most screw threads used on a bicycle use a 60-degree thread angle. For external threads (bolts), a right-hand thread slopes up to the right, but the internal right-hand thread slopes up to the left.
What is the thread angle on threaded pipe?
60°
NPT and NPS threads have a 60° included angle and have a Sellers thread form (flattened peaks and valleys).
Are Whitworth threads still used?
British Standard Whitworth (BSW) Thread Form. Sir Joseph Whitworth proposed this thread in 1841. The thread form is now redundant and has been replaced by Unified and Metric threads but there are many applications in which it is still used.
What does BSF thread mean?
British Standard Fine
British Standard Fine (BSF) is a screw thread form, as a fine-pitch alternative to British Standard Whitworth (BSW) thread. BSF threads use the 55 degree Whitworth thread form. It was introduced by the British Engineering Standards Association in 1908.
What is the most common thread angle?
Although the 60 degree thread angle of the U.S. and metric systems is the most common one, other angles have been used for vee form threads. The Lowenherz Thread uses 53 degrees 8 minutes, and the Swiss Thury and the British Association Threads use 47 – 1/2 degrees.
When did Whitworth stop being used?
Whitworth and BSF officially became obsolete in 1948 following an agreement between the UK, US, and Canada to standardise on the American UNC and UNF fasteners for future use.
Are BSF threads still used?
The thread form is now redundant and has been replaced by Unified and Metric threads but there are many applications in which it is still used. The British Standard Fine (BSF) thread has the same profile as the BSW thread form but was used when a finer pitch was required for a given diameter.
What are the dimensions of the 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 diameter in steps specified on a chart.
Is the British Association screw thread the same as the Whitworth standard?
Comparison of standards. The British Association screw thread (BA) standard is sometimes classed with the Whitworth standard fasteners because it is often found in the same machinery as the Whitworth standard. However it is actually a metric based standard that uses a 47.5° thread angle and has its own set of head sizes.
Which is better British Standard or British Standard Whitworth?
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.
Why did the British change the thread series?
Some years later the British decided they needed a finer pitch for some applications, so another thread series was introduced (same 55 degree angle). They also decided that the heads were too big for the bolts, so for most applications they switched to using the next size smaller heads.