thread dimensions

[dho]

i like to define a custom thread. 1,625 major diameter, and 56 pitch.
mil-s-8879 says the pitch diameter tolerance per ASTM B1-1. i could not find it in B1-1.
help me to find all the diameters/tolerance, major, pitch, minor, male and female.
thanks.

 

[drawoh]

dho,

If you specify 1-5/8-56UN, you can look up your tolerances in the Machinery's Handbook. This all assumes of course that I correctly guessed your units.

--
JHG

 

[dho]

thanks.
but the machinery handbook only lists up to 24 pitch, no finer.
if go by ASTM B1-1, table 19, for 1.625, LE, say .125, 56 pitch, the pitch diameter tolerance would be 0.001764 + 0.000530 + 0.001025 = 0.003319 for 2A, and 75% of it, .002489 for 3A.
right?

 

[drawoh]

dho,

You are looking at the table for Standard Series and Selected Combinations. I have the 26th edition here. The page immediately before this is called American Standard Unified Inch Screw Thread Form Data. This shows the thread form independent of the major diameter.

--
JHG

 

[KENAT]

Look in the FAQ section of this forum there is one on this very subject.

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

 

[tbuelna]

MIL-S-8879 only covers the UNJ thread forms (controlled root radius). Most of the dimension/tolerance formulas for a 56 tpi thread are covered in table I. MIL-S-8879 sections 3.4.2 (external threads) & 3.4.3 (internal threads) state that the threads shall be in accordance with FED-STD-H28/2 and ANSI/ASME B1.1 (class 3A & 3B). Regarding pitch diameter limits, the external thread max PD limit and internal thread min PD limit are given in MIL-S-8879 table VIII. The opposite PD limits can be found in FED-STD-H28/2 table II.C.2.

http://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=53604

 

[dho]

i have machinery handbook, 23rd edition. American Standard Unified Inch Screw Thread Form Data on page 1484 does not give the tolerance. i am afraid.
search the treads, one of them "How Do I Specify Unified Thread Form Custom Threads? by KENAT", but B1-1 table 31 thru 40, are for "coarser" thread than what i like to use due to the thin wall.
so, i think i still would go by B1-1, para 5.8 "...... apply to standard and SPECIAL series screw thread." and calculate per para 5.8.1 and 5.8.2 along with table 19 for 1.625-56UNS-2A, 2B.
thanks.

 

[KENAT]

dho, when you say 'treads' do you mean you looked at faq404-1480 which will show you how to dimension a UNS thread.

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[dho]

yes, i did read thread FAQ404-1480, but seems it did not direct me to the tolerance calculation.
is my saying posted at 12 Sept 16 13:03, wrong on tol cal ?
thanks a lot.

 

[KENAT]

Well kudos to you dho for being one of the only question askers who prefers to do his own math rather than click a link at the bottom of the FAQ to a site that claims to do it for you.

Machineries handbook or similar reference may have the tolerance calcs, else yes you'll need ASME B1.1.

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[dho]

of course i would like to have a calculator web page, also like to know the calculation behind. but i am afraid, that page

http://www.boltplanet.com/Un/un.asp?txtseries_page=UNS

does not calculate the tolerance.
thanks to KENAT for helping me.

 

[KENAT]

Hmm, it did when I used it. It's at the bottom of the pop up unless I'm missing something.

http://www.boltplanet.com/Un/un.asp...r=xxx&txtseries_page=UNS&submit=Calculate+Now

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[dho]

thanks KENAT.
it is weird. my clicking did nothing (Google Chrome). one interesting thing, "your" page, engagement length on top, my page nut factor on top.
i still will go over B1-1, calculate those and compare to "your" page.
thanks.

 

[KENAT]

Do you have pop ups blocked?

Posting guidelines faq731-376

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

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

 

[dho]

as i remember the browser would pop up a line to ask if you allow a pop-up. WAS that true?
my google chrome was set as pop up not allowed. your suspicion was right.
thanks.

 

[dho]

thanks again.