How to calculate equivalent cross-sectional area of thread contact? 2

[USAeng]

On #3-56 threads (small threads) how could you calculate the equivalent cross sectional area that would be made by the metal on metal contact in the threads for a given length of engagement?

If anyone can explain or just point me to a website I would appreciate it.

Thanks a lot.

 

[dinjin]

Try this url for inch or metric.

http://www.roymech.co.uk/Useful_Tables/Screws/Thread_Calcs.html

 

[unclesyd]

Here are three papers that maybe of some help.

http://www.wellheadservices.net/techdocs/Fasteners_Dimensions.pdf

http://www.hexagon.de/dose/form02e.pdf

http://www.hexagon.de/dose/dose-1e.pdf

 

[racookpe1978]

Remember the pull-out force will depend on how the threads are cut (100 % depth is very seldom achieved since that tends to break the tap; most taps are run in a hole that yields only about 60-75% theoretical engagement depth.)

Also, verify that the calculated pull out force will be accurate for your actual case: if both metals (male and female) are not the same yield strength, the weaker will yield first.

Nbr 3? That's an unusual size.