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How do you check your threads when threading on lathe ?

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  • JRouche
    replied
    Originally posted by 754 View Post
    When i started this thread I thought it was a home shop type thread and situation..
    so it was more of a do you look it up, or do you use nuts on hand.... and how do you store them ..that sorta thing.
    Sure there are always precision applications, but a lot of us dont encounter that.. sometimes ever.

    That said, i do enjoy single pointing and its challenges.. things like having to recut threads... re positioning the tool on a n existing thread... not so much fun if its internal or metric .. or things like doing a 1/2 or 5/8 feedscrew 20 or 24 inches long without a follow rest.....having to compensate fir the rod bending away from the tool.... a bit of challenge but rewarding to do .
    Thats refreshing, coming from you. A full time or regular machinist as are many here.

    What many here are, are not machinist.

    We may be from some other profession. Say a white collar worker that has a hobboy in his garage.

    It might include a lathe and drill press.

    Thats Us, Home shop machinist, doing our best... JR

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  • 754
    replied
    When i started this thread I thought it was a home shop type thread and situation..
    so it was more of a do you look it up, or do you use nuts on hand.... and how do you store them ..that sorta thing.
    Sure there are always precision applications, but a lot of us dont encounter that.. sometimes ever.

    That said, i do enjoy single pointing and its challenges.. things like having to recut threads... re positioning the tool on a n existing thread... not so much fun if its internal or metric .. or things like doing a 1/2 or 5/8 feedscrew 20 or 24 inches long without a follow rest.....having to compensate fir the rod bending away from the tool.... a bit of challenge but rewarding to do .

    Leave a comment:


  • nickel-city-fab
    replied
    Originally posted by eKretz View Post
    Yeah, it's pretty application specific when you get a job. For instance, something like a bearing locknut you need to be right on the money or you may add runout to the assembly when the nut is tightened. For garden variety fasteners on something like a hose clamp or what have you, you can do whatever you want...
    That's actually a great example, because at my old job I actually *was* the millwright.
    And yes, bearing fits and locknuts got measured and specced to the 4th place.
    Those $5,000 SKF bearings had to be spotless and spot-on.
    But I'm not gonna waste that kind of time and energy on a garden variety bolt for a pipe flange.

    In my home shop, the only time I need to mic a thread is if I need a very specific fit. Or if I'm making an oddball for some reason.
    Otherwise if it fits thru one hardware store nut, then you *know* it will fit thru every other hardware store nut, because that's how loose the spec is on those.

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  • DR
    replied
    Using a nut as a gage can be problematic. If your cut thread doesn't have the correct crest flat or radius you can go way undersize until a nut will screw on.

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  • eKretz
    replied
    Yeah, it's pretty application specific when you get a job. For instance, something like a bearing locknut you need to be right on the money or you may add runout to the assembly when the nut is tightened. For garden variety fasteners on something like a hose clamp or what have you, you can do whatever you want...

    What the customer doesn't want is to have one of their millwrights butcher that bearing locknut taking it off and then they buy a new one and it's a tight fit and it won't go on... Leading to more butchery by the millwright, etc.

    Or say a nut is in a tight place and the wrench can only turn ⅛ turn at a time. They will curse you every ⅛ turn if it's too tight and they can't turn it on all the way without a wrench until the last torque-up. It doesn't take much grime or grit to cause that either.
    Last edited by eKretz; 07-22-2021, 11:20 AM.

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  • Doozer
    replied
    I grab one random nut all the time...........
    Sometimes two....


    --D

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  • J Tiers
    replied
    Originally posted by nickel-city-fab View Post
    Since all of my nuts come from Ace hardware, and Ace has only 2A/2B then its safe to say its a 2A/2B fit. Exactly *where* it may be in the tolerance band is irrelevant IMHO as long as it is within its class of fit. And for 90% of the stuff "out there" it's plenty good enough.
    ............................
    Agree is is likely "good enough".

    But, by using a nut and roughly assessing the slop, you are employing a "one sided tolerance range". What you know is that the thread is small enough that the nut goes over it. It may be under size, all you know is that it probably is not over size.

    That is why there are Go/NoGo gauges. And no you do not need them for every thread, agreed without a fight. More of a pedantic point, but engineering and machining are full of pedantic points.

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  • nickel-city-fab
    replied
    Since all of my nuts come from Ace hardware, and Ace has only 2A/2B then its safe to say its a 2A/2B fit. Exactly *where* it may be in the tolerance band is irrelevant IMHO as long as it is within its class of fit. And for 90% of the stuff "out there" it's plenty good enough.

    Measuring the threads doesn't come into play until you are working to something much closer than that. Say con rod bolts for example. Those get measured.

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  • J Tiers
    replied
    Grabbing ONE random nut means you don't know where in the tolerance band it is. If you have a selection from different sources and lots, you have a better chance if you try them all, but ultimately, a measurement is what gets it done.

    For many things, fitting to the mating part is OK. it's when you do not have a mating part that you need to do everything to the numbers, or to a gauge that is known.

    Originally posted by polaraligned View Post

    At least with running a die for the last bit, I know the fit is correct for the class of fit I need........................... Either way, the die is faster and the fit is always right on.
    You don't have very many adjustable dies then?

    Europeans seem to like fixed dies, but just about all the dies in the shop here are adjustable. They need to be set up for whatever class fit is intended. And then they need to be locked, or else it has to be done every time.

    In the US, fixed size dies tend to be cheap imports (not always, of course), and it is anybody's guess what class thread fit those make.
    Last edited by J Tiers; 07-22-2021, 09:40 AM.

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  • nickel-city-fab
    replied
    Originally posted by JoeLee View Post
    Yeah, and how many times have you ever had to do that??? I have a few thread mics too, think I used them once for comparison purposes for some sensitive adjustment screws I had to make. The mating nut has always served as a go - no-go gauge.

    JL..............
    probably half a dozen times in the last several years...
    I would say once or twice a year I have to use the mics.
    It sure is nice to have them, tho.

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  • JoeLee
    replied
    Originally posted by nickel-city-fab View Post

    That's actually why I do it that way. I grab a random hardware store nut out of the pile and try it. If it fits like a generic 2A/2B hardware item, then it's good to go. Only time I use the mics etc. is when I have to for a close fit.
    Yeah, and how many times have you ever had to do that??? I have a few thread mics too, think I used them once for comparison purposes for some sensitive adjustment screws I had to make. The mating nut has always served as a go - no-go gauge.

    JL..............

    Leave a comment:


  • Doozer
    replied
    Originally posted by eKretz View Post
    You can't cut ID threads with wires... You can make your own thread gage with wires to fit and gage your I.D. threads. You can also buy I.D. gages that use an indicator that work sort of like a thread micrometer.

    You guys can fit nuts for threading all you want in the home shop, but that doesn't always fly for paying industrial customers. They want to be able to grab another nut from anywhere and have it fit. We're comparing apples and oranges in a lot of cases here.

    In a home shop situation fitting to a nut should be fine.
    Agree. At work we have thread plug gauges and thread ring gauges.
    For home shop things, I have often made a male plug by measuring
    the pitch diameter over wires, and used it to gauge an ID thread that
    I was cutting. First time I did this was years ago, when I was 25 years
    old, and had a 10" Atlas. I made a plug that was 1-1/2" -8 for checking
    a chuck backing plate I was making for it on the big lathe at work.
    Man, I do love threads. The sense of accomplishment when they fit
    just right is awesome. I try to block out of my memory the times that
    I opened the half nuts too soon and buggered it all ! LOL Ha ! ! ! ! !

    -Doozer

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  • nickel-city-fab
    replied
    Originally posted by eKretz View Post
    They want to be able to grab another nut from anywhere and have it fit.
    That's actually why I do it that way. I grab a random hardware store nut out of the pile and try it. If it fits like a generic 2A/2B hardware item, then it's good to go. Only time I use the mics etc. is when I have to for a close fit.

    Leave a comment:


  • eKretz
    replied
    You can't cut ID threads with wires... You can make your own thread gage with wires to fit and gage your I.D. threads. You can also buy I.D. gages that use an indicator that work sort of like a thread micrometer.

    You guys can fit nuts for threading all you want in the home shop, but that doesn't always fly for paying industrial customers. They want to be able to grab another nut from anywhere and have it fit. We're comparing apples and oranges in a lot of cases here.

    In a home shop situation fitting to a nut should be fine.

    Leave a comment:


  • JRouche
    replied
    I have a set of wires. Learned how to use them. I worked better with them on the bench then the lathe.

    I never cut any inside or out threads, single point to where I thought wires would improve the thread engagement. And thats what it comes down to. Thread engagement.

    I cut just as many internal theards and would like to make a tool to make that easy with wires

    And yes, as crazy as it sounds. I love to single point threads on my lathe. Just the way it is...JR

    Leave a comment:

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