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Metric Thread help needed.

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  • Guest's Avatar
    Guest replied
    Take a chill Pill Phil, it was not me who said it was "stupid", I am simply saying what is the convention used in industry. If you have an opinion otherwise then you are perfectly entitled to that, however this is the conventional used as an abbreviation for metric coarse.

    M10 is a truncated version of M10 x 1.5 which you could not guess at unless you were aware of the convention, which is quite possible in a home shop environment.
    If you are not aware of the convention, then hopefully now you are. It seems plenty of other people here who routinely work with metric fasteners are.

    Truncation and abbreviation are synonyms in this sense Phil, M12 is an abbreviation of M12 x 1.75. Communication of any description is risky Phil, indeed this very post drives that home. When I initially wrote M12 x 1.75 I mis-typed .75, had I simply written M12 the mistake wouldn't have occurred. Of course any experienced person in this field would question why it was not written 0.75, that also being convention!

    As for hamburgers, I shall certainly make a mental note to myself that you have no sense of humour.

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  • philbur
    replied
    Your analogies leave a lot to be desired. 12 o'clock is an abbreviation of 12 of the clock with all the necessary elements still there. RAM is an abbreviation of random access memory which you would not understand if you were not computer savvy. M10 is a truncated version of M10 x 1.5 which you could not guess at unless you were aware of the convention, which is quite possible in a home shop environment. The reference to the Hamburger is just stupid and kinda destroys you point right at the the end.

    Communicating information by virtue of it's absence will always be a risky business, especially when you are unaware of the knowledge of the person you are communicating with.

    This discussion started with somebody saying to use M10 x 1.5 was stupid. Well it isn't the accepted convention but it is far from stupid.

    Phil

    Edit: Is it stupid or wrong to use the phrase random access memory instead of RAM.

    Originally posted by Tanto
    Steve is quite right. It is convention to call only M10 etc when drafting. That does specify the pitch, since none is called it is therefore metric coarse. If the pitch is called, that act in itself implies something other than metric coarse. Of course it's possible to specify the pitch throughout if you want, however it would be like saying the time is 12 "of the clock", nobody gets confused when somebody says it's 12 o'clock, despite that also being an abbreviation used by convention. Do you also walk into a computer store and order your random access memory to upgrade your machine? Personally I order RAM, and I haven't instead been handed a hamburger or anything else instead of what I was expecting. No confusion required, it's all just convention.
    Last edited by philbur; 08-27-2011, 07:31 PM.

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  • Guest's Avatar
    Guest replied
    Steve is quite right. It is convention to call only M10 etc when drafting. That does specify the pitch, since none is called it is therefore metric coarse. If the pitch is called, that act in itself implies something other than metric coarse. Of course it's possible to specify the pitch throughout if you want, however it would be like saying the time is 12 "of the clock", nobody gets confused when somebody says it's 12 o'clock, despite that also being an abbreviation used by convention. Do you also walk into a computer store and order your random access memory to upgrade your machine? Personally I order RAM, and I haven't instead been handed a hamburger or anything else instead of what I was expecting. No confusion required, it's all just convention.

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  • SDL
    replied
    Originally posted by Carld
    Ok, so for drawing purposes if your using a coarse thread metric bolt all you have to print is M10 but if you want to spec. a fine thread you must print out M10-1.25mm.

    That's interesting but I wonder how many mistakes are made because of drafting errors? I would prefer to know the exact pitch of the thread rather depend on someone putting M10 on the print. I would be making a phone call at that point.
    That,s exactly how its been done at the 5 places I have worked at in the last 30 years in the UK and sounds like how its done in Finland but not Norway.

    Most of the problems I have had have been where the pitch for a fine series has been on the drawing but ignored, as it is just so rare in the industries I have worked in, I'm sure the fine series are common in Automotive and Aerospace etc.

    Most UK graduates now days don't even understand the tolerancing of limits and fits on threads.

    Steve Larner

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  • Carld
    replied
    Ok, so for drawing purposes if your using a coarse thread metric bolt all you have to print is M10 but if you want to spec. a fine thread you must print out M10-1.25mm.

    That's interesting but I wonder how many mistakes are made because of drafting errors? I would prefer to know the exact pitch of the thread rather depend on someone putting M10 on the print. I would be making a phone call at that point.

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  • philbur
    replied
    ISO 262 contains no reference to using only the diameter when making reference to course threads. As far as I can determine nor do the other 4 ISO standards relating to metric threads.

    Your wikipedia reference says "can omit". Not "must" or "shall omit".

    Phil

    Originally posted by SDL
    The Std is ISO 262 for those not allergic to Tiff links see here halfway down preferred sizes ( By the way welcome back tiff)

    http://en.wikipedia.org/wiki/ISO_metric_screw_thread

    For those allergic to wiki go here

    http://www.iso.org/iso/iso_catalogue...?csnumber=4167

    and the file down loaded for me no payment P4 Table 1

    And this

    http://www.carrlane.com/catalog/inde...2A36515F554A5B

    sets out quite well how USA ANSI always specifies pitch and the rest of the world (who understand and follow the standards) Don,t specify pitch if coarse.

    Steve Larner

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  • John Garner
    replied
    Boucher --

    If you haven't already ruled out an epoxy fix -- grease the male thread, degrease the female thread, coat both sides with mixed epoxy, assemble, and wait for the epoxy to cure -- with JB Weld, Marine-Tex, or any of a couple dozed similar products, consider it.

    John

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  • SDL
    replied
    Originally posted by Carld
    All the hardware stores I have been to have both fine and coarse thread metric and imperial bolts and nuts.

    I have never been to any store selling bolts and nuts that only have coarse or fine thread.

    I also have found few hardware store workers that knew much about bolts and sizes and grades. And, at 70 years of age I have been in a hell of a lot of hardware stores in several states.

    I have never heard of one thread pitch being "The Standard" size. On the other hand I am not an engineer nor do I do CAD so the "Standard" may only occur in those areas, not in everyday usage.
    The Std is ISO 262 for those not allergic to Tiff links see here halfway down preferred sizes ( By the way welcome back tiff)

    http://en.wikipedia.org/wiki/ISO_metric_screw_thread

    For those allergic to wiki go here

    http://www.iso.org/iso/iso_catalogue...?csnumber=4167

    and the file down loaded for me no payment P4 Table 1

    And this

    http://www.carrlane.com/catalog/inde...2A36515F554A5B

    sets out quite well how USA ANSI always specifies pitch and the rest of the world (who understand and follow the standards) Don,t specify pitch if coarse.

    Steve Larner

    Leave a comment:


  • Juergenwt
    replied
    Carld - it's a learning process. A little story about GM. When GM decided to go all metric (system preferred by US government) they tried to keep track of the cost for converting so they would be able for a reimbursement from the government. By the third year they stopped doing that because the saving far outweigh the expense. In the beginning they talked about zillions of dollars in cost. In the end they ended up with zillions in saving. One of the main reasons was the reduction in inventory from screws to cutting tools to print sizes etc..

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  • Carld
    replied
    All the hardware stores I have been to have both fine and coarse thread metric and imperial bolts and nuts.

    I have never been to any store selling bolts and nuts that only have coarse or fine thread.

    I also have found few hardware store workers that knew much about bolts and sizes and grades. And, at 70 years of age I have been in a hell of a lot of hardware stores in several states.

    I have never heard of one thread pitch being "The Standard" size. On the other hand I am not an engineer nor do I do CAD so the "Standard" may only occur in those areas, not in everyday usage.
    Last edited by Carld; 08-27-2011, 02:46 PM.

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  • Juergenwt
    replied
    Boucher - go to the next Hardware store and buy a M12 nut.

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  • Juergenwt
    replied
    Boucher - Get a standard M12 nut and try it and than order a standard M12 tap.
    Don't mix the two (inch and metric) systems. Those gages you show are made for the sales girls at Home Depot or Menards. For a professional they are useless. Whoever made those did not have a clue what he was doing. Those stores should not stock metric fine and the properly don't. If they do, they will not sell any for years to come. Remember what I said: reduce inventory!

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  • Boucher
    replied
    Update on thread fit.

    The bushing threaded to 15 tpi will screw onto the male metric thread. It snuggs up at 8 turns and gets tight at 9. It would have been nice to have a couple of metric nuts. I have imperial threads up to 3" but very few metric.

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  • Forrest Addy
    replied
    There are NO preferred imperial thread pitches close enough to metric to properly engage a metric nut unless you thread undersized. Some are close but 1.75 mm pitch works out to 14.51 threads per inch. Half in the middle. The result is loose, unsatisfactory, easily sheared, will work loose with a couple of shocks, and bogus.

    The alternative is Metric translation gears. $$ Boring teeny threads is a PITA anyway.

    Some battles are not worth fighting to a successful conclusion. Buy a cheap M12 tap and be done with it.
    Last edited by Forrest Addy; 08-27-2011, 02:11 PM.

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  • kc5ezc
    replied
    No worry about metric coarse or fine bolts or nuts here. ALL the stores only have one (1) pitch in stock. Usually coarse. Of course they will order some fine pitch and get them 'real soon now.' that means 72 hours to a week, maybe.
    Even the auto parts places seem to have only one pitch.
    Auto dealers may have the part, but under a manufacturers number. They do not know the pitch.
    It is only a 1 hour drive (one way)to a good nut and bolt place. Of course they are not open after 5 pm and on weekends.
    Rant off.

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