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thread dimensions

thread dimensions

thread dimensions

(OP)
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.

RE: thread dimensions

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

RE: thread dimensions

(OP)
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?

RE: thread dimensions

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

RE: thread dimensions

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...

RE: thread dimensions

(OP)
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.

RE: thread dimensions

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.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

RE: thread dimensions

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

RE: thread dimensions

(OP)
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.

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