7"-4NS2

[thehood1]

I have a job that ask for a nut to be machined with 7-1/2" rod with 7"-4NS2 Threads .Does anyone have the specs on this thread,ID,OD angle etc.A drawing would be great

 

[btrueblood]

NS was nomenclature from pre-WW2 American National Standard thread spec. The old style spec's. have been absorbed by the newer Unified National Stanard thread series. You need to make it to UNS specs., but check with your customer. See:

http://www.ring-plug-thread-gages.com/ti-N-vs-UN.htm

It looks like your thread spec. would be a 7"-4 UNS thread, class 2 fit.

 

[btrueblood]

Sorry, shoulda wrote:

"new thread spec. would be a 7"-4 UNS thread, class 2A fit.

 

[KENAT]

faq404-1480

Gives some guidance on properly specifying UNS threads.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[unclesyd]

Make sure you get the exact thread specification of the bolt threads as being a little off at your diameter can and normally does cause the threads to lock after 3 or 4 turns.

This is a little advice comes with the qualifier "don't ask me how I know that". I'll admit no guilt, but [pay the fine.

A little background. We had high pressure equipment designed (10,000 psig) that was designed and partially built pre WWII and the NS thread was the fastener standard on all the larger fasteners while UNS was used on the smaller fasteners. We had the same problem with our HNO3 plants as about half the fastens were Whitworth with the other half being UNS or NS.

The mixing of thread forms is one reason that the older mechanics would spin the nut on fastener before using, the other being to see if the fastener has been elongated if it was being reused.

 

[mrainey]

This thread has some good info.

http://www.eng-tips.com/viewthread.cfm?qid=92960&page=5

Software For Metalworking

http://closetolerancesoftware.com