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    Default Thread Quality

    My company taps thousands of parts on a daily basis. We use standard go/nogo gauges to check for product quality. We are now wanting to take that quality check to the next level. Does anyone know if there is a gauge or some kind of measurement system that can monitor the amount of torque/force a thread gauge needs to pass through the threads?

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    What diameters are your threads? That you only mention taps suggests only internal threads. Start using torque and you'll wear your gauges out faster than necessary.

    If the thread is correct then using any torque gauge is IMO a waste of time and money. Knowing where the pitch diameter is within the tolerance is basically the only important thing re "fit".

    Of course there's more to a good thread than "just" the pitch diameter but when a gauge has a problem then it's as good as always because it's either too close to the upper or lower pitch diameter tolerance.

    As to whether or not you can measure pitch diameter on your threads depends almost entirely on their diameter. What are your smallest and largest tapped threads?

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    Define your "next level"?
    You must have had quality issues, because otherwise why add time to a job = money?
    You shouldn't need any torque to wind a thread gauge in - it should be free running.

    What you can do...is the last component off the machine (so a 1 in 10? for instance) when checking with a screw plug thread gauge, also visual the thread for burrs and good finish (you may need a magnifying glass?).
    And at the same time, check the core diameter with pins, to ensure you're within tolerance.
    That won't add much time at all to you process, but maybe a step to solving any issues you have?

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    Quote Originally Posted by barbter View Post
    Define your "next level"?
    You must have had quality issues, because otherwise why add time to a job = money?
    You shouldn't need any torque to wind a thread gauge in - it should be free running.

    What you can do...is the last component off the machine (so a 1 in 10? for instance) when checking with a screw plug thread gauge, also visual the thread for burrs and good finish (you may need a magnifying glass?).
    And at the same time, check the core diameter with pins, to ensure you're within tolerance.
    That won't add much time at all to you process, but maybe a step to solving any issues you have?
    It's always a good idea to check (preferably measure) bore diameter as a thread plug gauge doesn't reveal if it is oversize. Unless the bore diameter is smaller than the tolerance (?) then torque won't be affected.

    Also worth noting is that the tolerance on the bore diameter is roughly twice the tolerance of the pitch diameter as far as metric and UN threads go.

    http://f-m-s.dk/1.08.pdf

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    Using the word "force" and "thread gauge" in the same sentence reminds be of those QC people that are determined to get the no go gauge to go as far as they can at all cost.

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    Quote Originally Posted by Dualkit View Post
    Using the word "force" and "thread gauge" in the same sentence reminds be of those QC people that are determined to get the no go gauge to go as far as they can at all cost.
    Have you ever known any "QC people" that would do that or do you just dislike "QC people"?

    I certainly agree with "Using the word "force" and "thread gauge" in the same sentence" is very wrong.

    If I had QC inspectors going from machine to machine it'd mean I didn't trust the guys operating the machines. I'm not saying QC isn't necessary but it should be used to help not "big brother is watching you".

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    Quote Originally Posted by Dualkit View Post
    Using the word "force" and "thread gauge" in the same sentence reminds be of those QC people that are determined to get the no go gauge to go as far as they can at all cost.
    Hmmm...you've worked "there" as well...

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    Quote Originally Posted by Gordon B. Clarke View Post
    It's always a good idea to check (preferably measure) bore diameter as a thread plug gauge doesn't reveal if it is oversize. Unless the bore diameter is smaller than the tolerance (?) then torque won't be affected.

    Also worth noting is that the tolerance on the bore diameter is roughly twice the tolerance of the pitch diameter as far as metric and UN threads go.

    http://f-m-s.dk/1.08.pdf
    No need to bold my sentence.
    I know that.
    That's why i wrote it.

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    Quote Originally Posted by Gordon B. Clarke View Post
    Have you ever known any "QC people" that would do that or do you just dislike "QC people"?

    I certainly agree with "Using the word "force" and "thread gauge" in the same sentence" is very wrong.

    If I had QC inspectors going from machine to machine it'd mean I didn't trust the guys operating the machines. I'm not saying QC isn't necessary but it should be used to help not "big brother is watching you".
    There are a lot of QC inspectors that think the more parts they reject the better they are going to look to their superiors. I worked at a place where every new line inspector, which appears to be what your referring to would frequently reject perfectly good parts. In a large company with quality management programs that can create a bunch of wasted time. I have nothing against reasonable highly skilled QC people, nothing wrong with having an extra set of eyes on things. Truthfully at most places I worked at QC people and machinists get along like dogs and cats.

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    Quote Originally Posted by Dualkit View Post
    Using the word "force" and "thread gauge" in the same sentence reminds be of those QC people that are determined to get the no go gauge to go as far as they can at all cost.
    Quote Originally Posted by barbter View Post
    Hmmm...you've worked "there" as well...
    Too many times to count I have had a QC guy come to me to get a thread no go gauge out or off a part. I think some of them try to use the O.D. ones as re-threading dies.

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    Quote Originally Posted by barbter View Post
    No need to bold my sentence.
    I know that.
    That's why i wrote it.
    That's not why I did it. Depending on the bore diameter of course then it's easier and cheaper just to measure when feasible and possible.

    Often it's only a question of seeing if the "flat" on the thread looks larger than it should. If in doubt then inspect or measure.

    OTOH the external thread OD and the internal thread ID are the easiest diameters to measure.

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    Quote Originally Posted by Dualkit View Post
    There are a lot of QC inspectors that think the more parts they reject the better they are going to look to their superiors. I worked at a place where every new line inspector, which appears to be what your referring to would frequently reject perfectly good parts. In a large company with quality management programs that can create a bunch of wasted time. I have nothing against reasonable highly skilled QC people, nothing wrong with having an extra set of eyes on things. Truthfully at most places I worked at QC people and machinists get along like dogs and cats.
    Any inspector I had that seemed to regard it as their "call" was to make life difficult for machine operators (and costing time and money) rather than what was best for the company would be looking for another job - at another company.

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    Quote Originally Posted by Gordon B. Clarke View Post
    That's not why I did it. Depending on the bore diameter of course then it's easier and cheaper just to measure when feasible and possible.

    Often it's only a question of seeing if the "flat" on the thread looks larger than it should. If in doubt then inspect or measure.

    OTOH the external thread OD and the internal thread ID are the easiest diameters to measure.
    Nope - this is not the preferred method for Aerospace/Automotive on the whole.
    Pins are the easiest functional check for the lower skilled among us - it goes, or it doesn't go.
    Measuring - which i presume you mean calipers - are no good for smaller holes. The flats on the faces give a false reading.
    Pins all the way.

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    We always check and record the minor diameter on internal threads with gage pins, both machinist and QC.
    This is a critical feature of thread quality.If the ID is blown out, you do not have a viable thread.
    If one of my guys said the thread was good because he saw the flats, he would be out on his ear.

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    Quote Originally Posted by barbter View Post
    Nope - this is not the preferred method for Aerospace/Automotive on the whole.
    Pins are the easiest functional check for the lower skilled among us - it goes, or it doesn't go.
    Measuring - which i presume you mean calipers - are no good for smaller holes. The flats on the faces give a false reading.
    Pins all the way.
    Maybe you missed it but I wrote "Depending on the bore diameter of course then it's easier and cheaper just to measure when feasible and possible."

    At the moment I have a customer whose smallest thread is M500. Of course he uses neither a tap or thread gauge.

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    Quote Originally Posted by Weasel View Post
    We always check and record the minor diameter on internal threads with gage pins, both machinist and QC.
    This is a critical feature of thread quality.If the ID is blown out, you do not have a viable thread.
    If one of my guys said the thread was good because he saw the flats, he would be out on his ear.
    Interesting. I'm guessing you either have special customers or machine expensive parts or both. What's the largest diameter threads you use pins for?

    I wonder how many shops know what the tolerance is on the thread bore diameter.

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    Quote Originally Posted by Christy K View Post
    My company taps thousands of parts on a daily basis. We use standard go/nogo gauges to check for product quality. We are now wanting to take that quality check to the next level. Does anyone know if there is a gauge or some kind of measurement system that can monitor the amount of torque/force a thread gauge needs to pass through the threads?
    Thats going to be by feel, if you have to grip the gage when spinning it into a thread then its too tight.

    the next level isnt a good way of saying it as all threads should be checked like follows

    Thread gages
    minor size pins
    Chamfer sizes and angle front and back if applicable.
    mold i.d. threads and view them on a comparator this will check thread form, root rad (this is usually done 1st article inspection and sampling size).
    Visualy look at thread for finish/smoothness.

    if your operators are checking thousands of threads its best to have 2 sets of gages one for inspection ones for shop. also inspection should be checking the p.d. on threads with wires to calibrate them from time to time. as thread gages do wear especially in alum.

    heres a tip if you already didn't know.
    if your parts are alum and you tumble them , the holes should be blown out extremely good with small tubed air nozzle that fits in the thread immediately after tumble if you wait till dry its too late.
    The inspectors should be using alcohol(or what your allowed) as a lubricant for checking threads during final inspection. don't run them dry as you will get one stuck or feel a gritty thread.
    Alum gets real dry after tumble and its not good for a dry thread gage to go into a dry threaded hole.

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    To OP.

    It occurs to me that errors in minor D, minor R, and pitch D will restrict "go" gages.

    For about 70$ each tool grinding shops will make any specials you want.
    Suggest getting a set of 5 gages, graduated, for minor D, and minor R, and pitch D, total 15.

    This would allow You to quantify where the errors are.
    100% confidence, pretty much.

    Then adjust your taps as needed, you did mention 1K/day quantities.

    Endless ways to use current taps, but very bad idea. Imo.
    In such quantities, it is very cheap to get custom taps made, for long-life use.

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    Quote Originally Posted by Gordon B. Clarke View Post
    Maybe you missed it but I wrote "Depending on the bore diameter of course then it's easier and cheaper just to measure when feasible and possible."

    At the moment I have a customer whose smallest thread is M500. Of course he uses neither a tap or thread gauge.
    Repeat - NO i didn't miss it i was keeping this on track because the OP originally said they tap '000s of threads a day.
    Which means tap = smaller holes, and not big holes which are threadmills.

    Why do you feel the need to keep deleting the stuff i write - you ask me a question i answered it and you delete it.

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    Quote Originally Posted by Gordon B. Clarke View Post
    I wonder how many shops know what the tolerance is on the thread bore diameter.
    All of them.
    Otherwise they'd go out of business.
    And standard practice calls it a thread core diameter, not a thread bore.

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