How to center ext. thread to int. thread?
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    Default How to center ext. thread to int. thread?

    Alrighty, one question from the bottom drawer: how can I remove all play from a pair of threads so that the axes of external and internal thread coincide?

    I have one-inch dia. threads, pitch is 1/32". Lengths around ¼ in. Transverse loads go up to a pound or so.

    Between the largest internal and the smallest external there’s not little play. A cheap, safe, and reliable method is what I’m looking for. At the moment I’m fiddling with tin and brass foils. Does anyone have any experience with lead foil? Brass leaves are available as thin as 2.4 tenths, yet the often rough surfaces shred the thin metal to tinsel. Aluminum foil can be had dirt cheap but that metal also flakes all over the p(a)lace. Mechanical alterations to the threads are not allowed. Somewhat at a loss, M.

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    Guess I don't understand the question.
    Have enough Od to skim after OD threading.
    Run the parts dead true like with one end on a dead center and the out end in a steady. Yes, a male or female center would do nicely.

    An intersecting bevel at the ID lead with the two threads axialy straight.

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    I’m not the maker of the threads, they exist already. Deal is how to center threaded parts one with the other. How to take out play in any case.

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    Lots of options if you could modify at least one part. I didn’t see it specified if the thread must be left free. If not a sort of jam nut should cause the treads to become reasonably concentric. Or if u had a way to hold them centered while some epoxy set up between the parts.

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    Quote Originally Posted by Mechanola View Post
    I’m not the maker of the threads, they exist already. Deal is how to center threaded parts one with the other. How to take out play in any case.
    Perhaps have the maker turn the parts between centers so the threads run axially correct to center. yes likely more costly.

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    Could you use an expanding 5C collet? Cut the correct thread in the
    expanding part of the collet.

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    Can you plate, oxide coat or anodize them to build up the thread surfaces?

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    Quote Originally Posted by Mechanola View Post
    Alrighty, one question from the bottom drawer: how can I remove all play from a pair of threads so that the axes of external and internal thread coincide?

    I have one-inch dia. threads, pitch is 1/32". Lengths around ¼ in. Transverse loads go up to a pound or so.

    Between the largest internal and the smallest external there’s not little play. A cheap, safe, and reliable method is what I’m looking for. At the moment I’m fiddling with tin and brass foils. Does anyone have any experience with lead foil? Brass leaves are available as thin as 2.4 tenths, yet the often rough surfaces shred the thin metal to tinsel. Aluminum foil can be had dirt cheap but that metal also flakes all over the p(a)lace. Mechanical alterations to the threads are not allowed. Somewhat at a loss, M.
    Taper and thread both parts. Provide a draw-up shoulder.

    Some lathe spindle noses have the tapered thread. Even more have a registry.

    So does most "drill steel" as in water and oil wells, not "helical-twist."

    It just isn't that hard.

    Your application, with the short traverse, is actually a "natural" for that technique.

    Works a treat.

    Doing it well... and on a VERY similar diameter AND run-length AND in 32 TPI... even got me my first real job!

    1960.

    But that was for ONE.



    Page two:

    BEST way - if volume-production is on the dance card, is "Not at all"

    - Put a register at BOTH ends, "synced" to a close match. EASY fit to hold to a tight tolerance. O-rings might even be OK?

    - Threads CAN now be loose. They only effect traversal.

    - both ends run up onto their registers for VERY close alignment.

    - even gas or liquid tight seal.

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    Quote Originally Posted by Mechanola View Post
    Alrighty, one question from the bottom drawer: how can I remove all play from a pair of threads so that the axes of external and internal thread coincide?

    I have one-inch dia. threads, pitch is 1/32". Lengths around ¼ in. Transverse loads go up to a pound or so.

    Between the largest internal and the smallest external there’s not little play. A cheap, safe, and reliable method is what I’m looking for. At the moment I’m fiddling with tin and brass foils. Does anyone have any experience with lead foil? Brass leaves are available as thin as 2.4 tenths, yet the often rough surfaces shred the thin metal to tinsel. Aluminum foil can be had dirt cheap but that metal also flakes all over the p(a)lace. Mechanical alterations to the threads are not allowed. Somewhat at a loss, M.
    Plate / spray. Lap / grind

    You're not giving enough info. How tight, will be opened often,seals anything etc.....

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    Tight fit internal threaded "dummy" to screw the threaded piece into and then do the internal thread?

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    60 degree threads should self center fairly reliably when tightened; do you need there to be no play when they aren't tight?

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    If the parts don't need to be disassembled there are plenty of high strength Loctite products that would work great. Simply apply and then fixture the parts for concentricity until it cures.

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    Quote Originally Posted by Orbital77 View Post
    Plate / spray. Lap / grind

    You're not giving enough info. How tight, will be opened often,seals anything etc.....
    Teflon tape. even?

    We'd surely be in deep trouble it didn't seal 99% of all the gas and liquid tight threaded joints all over the globe!


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    If I understand the question correctly, and the threads are already concentric to each other. I would look at using springs to pull one component to draw it up "square" on the flanks of the mating threads. This would remove any backlash as long as the spring was stronger than the force acting on the threads. Additionally, (in my mind at least) the axial slop would be removed from the threads forcing them to be coaxial with their mating thread.

    If I don't understand the question, sorry for the word vomit.

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    Quote Originally Posted by thermite View Post
    Teflon tape. even?

    We'd surely be in deep trouble it didn't seal 99% of all the gas and liquid tight threaded joints all over the globe!

    On second thought yes, it could be a water pipe....

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    Quote Originally Posted by Mechanola View Post
    I’m not the maker of the threads, they exist already. Deal is how to center threaded parts one with the other. How to take out play in any case.
    I think everyone needs to read this post again.

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    Quote Originally Posted by Gobo View Post
    I think everyone needs to read this post again.
    Can we please have beer and pretzels and take a nap instead?

    Or at least be allowed a "fool's errand" chit and a parachute so we may bail-out of the dirigible and go for a piss?

    When a SWISS craftsman starts asking amateur optimists how to use loose-fitting threads to assure precision concentricity?

    The whole freakin' WORLD has turnt upside down!

    TiG the f**ker. Machine it true. End of problem?


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    Silver plate.
    It is typically used to prevent galling I believe, but in one of the parts I make it is used to take out any and all play/vibration
    as it's only hand tightened and is used on a jet engine test station.
    You only need to plate one member, probably the internal is better.

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    Quote Originally Posted by SeymourDumore View Post
    Silver plate.
    It is typically used to prevent galling I believe, but in one of the parts I make it is used to take out any and all play/vibration
    as it's only hand tightened and is used on a jet engine test station.
    You only need to plate one member, probably the internal is better.
    Or Indium?

    Miccrolloy Bronze. Buggers offer it standard up to 100 thou.

    They can DO a full THIRD of an inch!

    Or a mere flash, "a 'tenth" is standard & common.

    Flexible application stuff. Wears well. REALLY well!

    https://www.kcjplating.com/miccrolloy-bronze-plating/

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    Thanks to you all.

    I thought it were clear what the goal is.

    It’s about optics. I have a lens and a camera with a turret, say a Victor, a Bell & Howell Filmo 70, a Paillard-Bolex H, an ETM P. These have critical focusing aids built in. The camera is mounted on a rack-over device, Bell & Howell called their accessory Focusing alignment gauge. A lens is turned to the position in front of the focuser, the camera slid to the side. Now I can frame and focus. Next I turn the turret plate to take the lens before the exposure aperture and move the camera to the other side of the rackover support (same distance as lies between two turret ports). The lens occupies the position it had when I framed and focused.

    This whole thing affords great accuracy with close-up and macro shots. The threads, however, do not center. Lenses end up within the play in any direction, so I have a problem. The camera is shifted in a linear way but the turret moves around its center, meaning the lens changes position angularly.

    I want to have a precise setup, therefore the lens closely centered in the female turret thread. From the standard for Unified Imperial 1“-32, ANSI/ASME B 1.1-1989, play with major Ø is at least 0.0011“ and 0.0098“ max., metric between 0,02794 mm and 0,24892 mm or as tolerance 0,22098 mm.

    Can the air be taken out with lead foil? I am seeking the right material for a temporary use.

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