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Thread: Okay - when did 1" UNF threads change???

  1. #11
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    Quote Originally Posted by ckalley View Post
    I just checked on the Mc Master web site. In hex head bolts, they only have 1"-14 NF , but they have both 1"-12 and 1"-14 taps. Go figure!
    Craig
    however,socket head 1 inch in 12&14 threads

  2. #12
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    FWIW, my ancient Patience and Nicholson wall chart lists 1x12 under UNF and 1x14 under UNS (Unified Special, a "standard" about which there seems to be a good deal of misinformation on the Internet). The preferred drill sizes are 59/64" and 15/16" respectively. Curiously, the British Standard Fine thread is coarser than either, at only 10 TPI.

    CCWKen, alas, you're in no danger of a metric infiltration—for some reason I cannot guess, standard metric threads go from 24mm direct to 27. As 1"=25.4mm, there's no close metric thread equivalent for bolts, though there is a standard metric conduit thread of 25x1.5.
    Last edited by Mike Burch; 05-15-2018 at 07:44 PM.

  3. #13
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    Quote Originally Posted by kf2qd View Post
    ....................... the thread is 1"-14... So, Just when exactly did this change? p....
    I can tell you that I started with a Die company in 1985 and the company had switched over "then" to 1"-14, but the old prints showed 1"-12

    So I would guess between 1973 and 1985

    Rich

  4. #14
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    Quote Originally Posted by ken View Post
    This on bite me in the butt a while back customer gave me a print with a 1" Fine hole he didn't list the TPI on the print. So I look on the thread chart and it lists 1" 12 as fine so I get the hole taped. He comes by with the bolts for the project and they don't fit there 1"14. luckley I only did the one of 4 of the parts as we only had the metal to do one at that time. 1" 12 is crossed off all my thread charts you can't find 1" 12 bolts in Portland OR. Wwe were going to make all the parts 1"12 but after a few phone calls we scraped the part. Ken
    Just curious but who paid for the scrapped part? The customer, because he failed to specify the thread fully, or you, because you didn't know that whatever the standard says, accepted custom and practice is 14TPI?
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  5. #15
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    Default Make them initial the drawing.

    Quote Originally Posted by ken View Post
    This on bite me in the butt a while back customer gave me a print with a 1" Fine hole he didn't list the TPI on the print. So I look on the thread chart and it lists 1" 12 as fine so I get the hole taped. He comes by with the bolts for the project and they don't fit there 1"14. luckley I only did the one of 4 of the parts as we only had the metal to do one at that time. 1" 12 is crossed off all my thread charts you can't find 1" 12 bolts in Portland OR. Wwe were going to make all the parts 1"12 but after a few phone calls we scraped the part. Ken
    There is some kind of stupid rule somewere, written by an idiot,concerning metric thread pitch.So when the "' blue print drawer",says m10 thread,YOU are automatically supposed to know what pitch tap to use.So you have a $5000 part and the "DESIGNER",Doesn't put the pitch on the thread. The customer or the foreman or the estemater,might get upset if you want to clarify the thread pitch.But if you tap the wrong thread they will all point the finger at YOU.Edwin Dirnbeck

  6. #16
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    Quote Originally Posted by Edwin Dirnbeck View Post
    There is some kind of stupid rule somewere, written by an idiot,concerning metric thread pitch.So when the "' blue print drawer",says m10 thread,YOU are automatically supposed to know what pitch tap to use.So you have a $5000 part and the "DESIGNER",Doesn't put the pitch on the thread. The customer or the foreman or the estemater,might get upset if you want to clarify the thread pitch.But if you tap the wrong thread they will all point the finger at YOU.Edwin Dirnbeck
    Metric threads are always the "standard" pitch unless specified otherwise.
    Not like your stupid 1" UNICORN-F

  7. #17
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    Quote Originally Posted by MattiJ View Post
    Metric threads are always the "standard" pitch unless specified otherwise.
    Not like your stupid 1" UNICORN-F
    Yeah, except when they are not. I keep finding references to "preferred", not "standard" metric sizes, and most (but not all) have a specified coarse and fine pitch.

    What most people refer to as the "standard pitch" for a metric size is really the "coarse" thread. The result is that you can not grab an M10 screw and know for certain that it's got a 1.5mm pitch. It might be 1mm pitch (the fine standard) or 1.25mm (the OTHER fine standard. And, of course, it could be some bastard that has a nominal diameter of 10mm but a much finer or coarser pitch. That last would not be an ISO metric pitch but could easily match the ISO thread form.

    If I wanted to make sure that a fastener was correct, I'd specify the nominal size, pitch(or tpi) and length along with the grade. Yes, there should be defaults for each, but why trust it to the memory of some tired worker to pick the right one when it can be specified in a few strokes of a pencil?
    Measure twice. Cut once. Weld. Repeat.
    ( Welding solves many problems.)

  8. #18
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    Ok, it's thread drift, but if the thread is designated by M<diameter> then it's always the coarse thread.

    Back on the original thread, all my UK references state that 1" UNF is 12TPI with no "optional" 14tpi variant...

  9. #19
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    95% of the world's machinists have no problem with the concept that M10 on a drawing means and ONLY means 10 x 1.5. Why is it so hard for the other 5% to grasp this?

    Quote Originally Posted by Edwin Dirnbeck View Post
    There is some kind of stupid rule somewere, written by an idiot,concerning metric thread pitch.So when the "' blue print drawer",says m10 thread,YOU are automatically supposed to know what pitch tap to use.So you have a $5000 part and the "DESIGNER",Doesn't put the pitch on the thread. The customer or the foreman or the estemater,might get upset if you want to clarify the thread pitch.But if you tap the wrong thread they will all point the finger at YOU.Edwin Dirnbeck

  10. #20
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    Quote Originally Posted by bob ward View Post
    95% of the world's machinists have no problem with the concept that M10 on a drawing means and ONLY means 10 x 1.5. Why is it so hard for the other 5% to grasp this?
    There does indeed seem to be a recognised rule that metric threads such as M10 means the coarse pitch (1.5mm in this case) and anything else should be specified as, for example, M10 x 1.0. Seems perfectly sensible, though I don't know if this is just accepted practice, or if its enshrined in the Standards somewhere.
    Enough of the devilish metric system and its iniquities. Lets get back to the original problem, which is that in the good old US of A, there is a thread 1" x 12TPI, defined in the standards and textbooks for many years, for which taps are readily available, but nuts and bolts are not. Nobody uses it, they all use 1" x14TPI, which isn't in the Standards. What sense is this? If there is a good reason for using 14TPI instead of 12 TPI, did no one ever think of revising the Standard?. Or is this a sneaky trick to get a laugh at stupid foreigners ( everyone outside the good old US of A) who don't know better and will use 1" x12TPI, then find nothing fits it?

    I know the UK system isn't perfect, but all you do is specify 1" Whitworth for a coarse thread, and 1" BSF for the fine thread. Simples.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

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