About the Screw Thread

Metric!

It is Metric 24 mm diameter but the pitch has not been specified

Dear Mr.Jacky Lee,

1. The letter ' M ' denotes for Metric standard thread , means major diameter of threads is equals to 24mm size.

With metric threads, the pitch is not specified when referring to the coarse pitch thread for the particular diameter.

Metric = 24 millimeter, refers to the outer diameter or the hole drilled, where the bolt passes through. Most developed countries in the world use this Metric standard for bolts. The metric sized bolts come with different threads: The advance of the thread is how much the bolt moves expressed in millimeter, turning it 1 turn. Example: M24 2 means a thread of 2mm (for one turn) Pitch is typically from the Standard system where they count the threads per inch lenght.

Thank you, good answer.

Technically, "Pitch" properly refers to distance crest-to-crest or valley-to-valley, and would be 2 mm in your example. What the inch-based Traditional British or Standard system calls "pitch" is actually the inverse of pitch. For example, a 1/4-20 ["quarter-twenty"] screw is 0.250 inch in outside diameter and has 20 threads per inch; its actual pitch is 0.050", but you'll never find it described that way.

As already said, M stands for metric.

But there are some errors related to pitch. According to ISO 261 and 262, if the pitch is the "coarse" one, can be omitted. So M24 means a metric thread with 24 mm of nominal diameter and 3 mm pitch. It can be designed also as M24 x 3.

If you should choose the "fine" pitch, then you must specify it: M24 x 2

Regards

If it is available, get a copy of the "Machinist Handbook." Very valuable to engineers and machinists alike.

It means you have found yourself in possession of a piece of crappy european garbage! =b But hey, at least it isn't a Whitworth thread, that would mean you were in possession of a piece of British crap!

And this crappy post indicates that Rorschach is a crappy engineer - mindless drivel has no place on here, Sir.