THREAD DIMENSION

[MCFELIX]

Hello members i need little bit help, i am confuse i need to make a 1.4375-12UN 3A the major diameter is 1.4263---1.4371 and pitch dia. 1.379---1.3834 everthing is ok but i understand UN in no control root radious i used .003 rad inserts but the minor diameter in to loww .010 tausands to reach the minor diameter i need used .008 or .009 tausand rad. anybody have this situation before thaks all members

 

sorry for the mistake felix

[Guest]

Are you trying to control the root diameter of the thread?

 

I don't know about anyone else but I always cut the major and the pitch, the root as I understood it is a theoretical diameter.

[MCFELIX]

i know i take my first piece to show the coustumer,because is 1st article but he tell me need to meet the prints dimension and the print show 1.3353 and my part have 1.324 major diameter is ok and picht diameter is ok too ,the unjf and others i know is control root rad but un i think is no necesary

[Guest]

Unnecessary perhaps, but if that is what your customer is looking for, I think you'll have to give it him.

 

 

JM2C

[mrainey]

What tolerance does the customer give you? I can't find one for a UN thread. It's really supposed to be a reference dimension, I believe.

[MCFELIX]

hello MRAYNEY yes the costumer give me the major 1.4263-1.4371 minor 1.3353

and p.d 1.3794-1.3834

[mrainey]

Yes, but no tolerance for the minor diameter. I guess you could lay the thread out in CAD and figure out what combination of root radius and pitch diameter will get you closest to 1.3353 on the minor, then hope you can find an insert that gives you what you need.

 

It's interesting that on a 1.4375-12 UNJ thread you get .0095 total tolerance on the minor diameter, but only .0044 on the pitch. You're going to have to hold both to the closer tolerance.

[TFesta]

The minor diameter on a standard 60 deg. OD thread is a maximum diameter. All you need is to check the OD, pitch dia. and use a thread gage. A thread gage is much better then the pitch dia.

[mrainey]

quote:

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The minor diameter on a standard 60 deg. OD thread is a maximum diameter.

---

His problem is that the customer won't accept that interpretation, right or wrong.

[CR]

Hi Felix

 

Use a thread insert with a 0.010R +/- .001

Like kennametal # NTC3R12E this will give you the right minor dia

 

If you want the one for the "J" thd it will be

Kennametal # NJP3014R12 (.0125/.0135 R)

[TFesta]

I understand what he is saying. He needs to show the customer why he is getting that dimension. Cause that's how it comes out. You can't have it both ways, it just don't work like that. Good luck you him. Hope the customer understands.

[MCFELIX]

OK Members i found answer for this issue.the client convert un to unjf we want all dimension relate to the print my minor diametere is now 1.3318---1.3413 Mrayney is right i need used big rad in the insert thankyou for all you reply