S.A.E - Standard American Engineers. Now it is called as UNF i.e. Unified Fine threads.
UNF (Unified Fine Thread)
Standardised in 1918
Angle of Thread 60o Degrees
Unified Fine (UNF) and Unified Coarse (UNC).
American threads consist of two common and easily obtained thread patterns known as U. N.F and U.N.C.U.N.F [national fine] is exactly the same as the old S.A.E [standard American engineers] that existed before threads were unified.
U.N.C [national coarse] roughly derived from the British Whitworth have the same pitches except 1/2 in dia where Whitworth is 12tpi and U.N.C is 13 tpi.
Both these threads are 60 degree angle
Early Harley and Indian motorcycles used 24tpi threads on most diameters
5/16 and 3/8 UNF are both 24tpi but 1/4 UNF is 28 tpi and a special 1/4 x 24 thread must be used.
7/32 x 24 UNC is an obsolete thread. In the late 1960's, when even the U.S. was thinking of going metric, the giant BSA corporation decided it was finally time to scrap the 19th Century Whitworth-based system, and switch to American. Since they had lots of money invested in tooling, the switch wasn't made suddenly (or completely), so bikes and cars from the late '60's and later had a mix of all sorts of thread forms. Typically, engine internals (e.g. the thread on the end of a camshaft) stayed with whatever form it used to have, while simple fasteners (e.g. holding the mud guards on) switched to UNF.
§ Screw threads have better compression strength than other threads. § Due to low thread angle there is no radial pressure on nut. § Due to smaller angle, the lead of screw is less.
The pitch of a screw thread is a measure of how closely the threads are spaced. It can be expressed as the number of threads per unit length (32 threads per inch, for example) or as the distance between two threads ( such as .8 mm).
As I recall , 3 full threads is minimum engagement length
It is easier. The question is not complete enough to be answered. The word EASIER needs to be further defined. so the question should read: What is easier to [add information here]; more screw threads or less screw threads?
knuckle threads are used in railway carriage couplings.
a screw with closely spread threads
the threads determine the depth the screw should move
screw thread are single threads which means they are not double
A screw is a fastener that is similar to a nail, but it has threads.
The hole that you put a screw into is referred to as a "tapped hole". The rib-like things in the hole are called "threads" or, more specifically, "internal threads" as opposed to the external threads on a screw.
The threads of the screw as the threads are turned by the screwdriver .
The threads are what make it work. As you will know if you have tried to use a screw with stripped threads, it is useless. That is because a screw is a simple machine built from an even simpler machine: the inclined plane. The threads are an inclined plane wound around the outside of the screw, and are what change the twisting motion into a lifting motion.
Metric threads are called that way, because you measure the distance between the threads (at the highest point), in millimeters., As opposed to SAE (standard), which are measured by the number of threads in an inch.
§ Screw threads have better compression strength than other threads. § Due to low thread angle there is no radial pressure on nut. § Due to smaller angle, the lead of screw is less.
§ Screw threads have better compression strength than other threads. § Due to low thread angle there is no radial pressure on nut. § Due to smaller angle, the lead of screw is less.
The pitch of a screw thread is a measure of how closely the threads are spaced. It can be expressed as the number of threads per unit length (32 threads per inch, for example) or as the distance between two threads ( such as .8 mm).
As I recall , 3 full threads is minimum engagement length