1.125 -13unja pitch diameter 1

i need to find this information

 

[boo1]

The standard thread form for 1-1/16" is 8 unc or 12 unf.

The 13 unj thread form data can be found in the Machinery Handbook, in the 25ed pp1638 table 1 or mil-hdbk-28

 

[Kenneth]

As alluded to by boo1, this thread callout appears fundamentally flawed on multiple fronts.

"A' in a thread callout usually indicates an external thread (with "B" designating internal), but is used in conjunction with a tolerance "Class" number:

"1.125-12 UNJF-3A"

Your callout doesn't include a tolerance class, which you must know to determine the pitch diameter limit dimensions.

The "J" thread form is a modified thread form (from the "UN" and "UNR" thread form defined in ASME B1.1) with a controlled, tangent root radius on the external thread, and an increased minor diameter on external and internal threads. It is usually specified in fatigue critical applications.

The current edition of FED-STD-H28/4 (

http://131.82.253.19/docimages/0000\59\68\53605.PD6),

which covers UNJ threads, refers you to MIL-S-8879 (

http://131.82.253.19/docimages/0000/35/17/7373.PD5).

I can't lay my hands on an old copy of H28, but I don't think it would be substantially different than MIL-S-8879.

For this thread diameter, MIL-S-8879, AS 8879, ASME B1.15 and ISO 3161 all tabulate dimensions for the following "graded" diameter/pitch combinations:

UNJC: 1.125-7
UNJF: 1.125-12
UNJEF: 1.125-18

and the following "constant", or "uniform", diameter/pitch combinations:

UNJ: 1.125-8
UNJ: 1.125-16

MIL-S-8879, AS8879, ISO 3161 and ASME B1.15 all describe/define the "J" thread form. Note that MIL-S-8879, AS 8879 and ISO 3161 only cover tolerance Class "3" ("-3A" and "-3B&quot threads. ASME B1.15 includes dimensions for Class "2" threads ("-2A" and "-2B&quot threads in addition to Class "3". The internal and external pitch diameters of a given thread tolerance class are (currently) identical to the dimensions in the "mother" ASME B1.1 thread document.

If this is truly a 1.125-13 diameter/pitch combination (which I tend to doubt) it should be designated as a "UNJS" thread ("S" for Special), the dimensions should be calculated per the relevant specification (See Table VIII for MIL-S-8879) and the calculated major, pitch and minor diameter limits (in addition to the root radius for external threads) should be tabulated on the drawing.


boo1: Darned if I can find any UNJ data, or info for a "13" constant/uniform thread series, in my 26th ed. Machinery's. Am I overlooking it, or is this another case of useful information being stripped from Machinery's in a new edition? My 25th edition is at home...

 

[Kenneth]

Just looked at my Machinery's at home and it's the 22nd edition, not the 25th...

 

[boo1]

Amerianan Standard Unified Inch Screw Thread Form Data

TPI 13
Pitch=0.07692
Depth of sharp V-thread 0.06662
Depth of Int Trd and Un Ext Trd 0.04164
Depth of Unr Ext Thd 0.04580
Truncation of Ext Thd Root 0.01655
Truncation of UNR Ext Trd root 0.01249
Truncation of Ext Trd crest 0.00833
Truncation of Int Trd root 0.00833
Truncation of Int Thd crest 0.01665
Flat at Ext Thd Crest and Int Thd Root 0.00962
Basic flat at Int Trdn Crest 0.01923
Max Ext Trd Root Radius 0.01110
Addendun of Ext Thd 0.02498

 

[Kenneth]

My confusion, boo1. In your original post, I thought you were referring to (and I was looking for in my Machinery's Handbook) either:

1) Information specific to the "UNJ" thread form, or,

2) Tabulated information (pitch diameter limits, etc.) for this specific diameter / thread pitch combination of any "unified" thread form.

I did not realize you were referring to the "basic" or "nominal" thread profile data used to calculate those dimensions.

While some of the basic thread profile dimensions in your post are shared with the UNJ thread form, the modifications made to the "UN" thread form to create the "UNJ" thread form mean some of them are not (Example: Depth of Internal and External Thread, Truncation of External Thread Root, Basic Flat at External Thread Crest, External Thread Root Radius Limits).

As stated in my original post, were this truly a 1.125-13 UNJS thread, the dimensions should be calculated per the applicable specification (Table VIII for MIL-S-8879). The "Basic Thread (Profile) Data" used in those calculations should also be specific to the UNJ thread form (Table 1, pages 16 and 17, of MIL-S-8879 for threads per MIL-S-8879).

 

[boo1]

That would be a very ODD thread size though.

 

[Kenneth]

Absolutely.