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Thread: 'Custom' Tool question: Measuring Manifold nut inside angles?

  1. #1
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    Default 'Custom' Tool question: Measuring Manifold nut inside angles?

    Folks,

    I encounter a lot of different manifold nuts of a lot of different models, and it seems now some reproductions vary significantly from OEM on the inside angle.

    It is easily accommodated if it can be accurately measured.

    This is posted in "Custom Tools" because I probably must make the instrument, but I haven't a clue what it would look like.

    Any ideas?

    Thanks in advance as always,

    ....Cotten
    Last edited by T. Cotten; 07-25-2017 at 12:25 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  2. #2
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    So then,....

    How would a "pro" measure it?

    Geometry isn't working for me.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #3

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    With a CMM.
    MARK

  4. #4
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    I would get a rough idea of the angle using a protractor, then I would mount it to an angle block. Put the angle block on a sine plate and adjust it until the angle was parallel with the surface plate. Or cut one in half and use an optical comparator.
    Bob Rice #6738
    He that conquereth his own soul is greater than he who taketh a city.

  5. #5
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    Thanks Mark!

    What's a CMM?
    (And is it affordable?)

    And Big Lake Bob!

    What kind of protractor, or angle block fits inside of a manifold nut?
    (Some are only 1 5/16" ID.)

    My customers aren't anxious to cut up their vintage hardware, and cutting up new ones is pretty expensive, particularly if you never know what angle the next batch will be.

    The problem arose when a fellow's mass-produced PEEK seals failed in modern nuts.
    (I have never had an issue with my machined seals, but then I don't use any of the same parameters.)

    So I cut some round stock to 60, 61, 62, etc., inked the bevels, and rubbed them into various nuts, OEM and reproduction.
    Two degrees is significant, and apparently enough to make a seal fail.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  6. #6
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    You could make a casting of the angle, and lip of the manifold nut with Bondo. With careful casting of just a section of the inside of the nut, you might have enough of a sample to measure the angle. I've had this same problem with trying to determine an angle inside a gland nut, or packing nut. . . . Tough nut
    Eric Smith
    AMCA #886

  7. #7
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    I considered sealing wax, Eric!

    But the bevel is actually wider than the ID of the threads. I would have to break it out, and once again, we do not want to damage the hardware.

    So then I thought if I could put a dial indicator in my toolpost set at 90 to the nut in the chuck, I could measure the geometry accurately enough, but no.
    One arm of the indicator is fixed, and cannot follow the bevel.

    Perhaps I'll hold it with a spring.

    ....Cotten
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    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  8. #8
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    DSC05681.jpgDSC05682.jpg
    Tom, this is the method I was talking about to roughly check the angle, and NO, the protractor is not set at the manifold angle. Just quick pictures to show there is an available means. I like your lathe set up to check the angle, but why not use a standard dial indicator and run it back and forth using the compound while adjusting the angle on the cross slide until the indicator reads '0' all the way across the angle. Looks like a quick easy means to me, great simple idea.

    And may I suggest that if you use your lathe setup as you pictured, turn the nut 180*. It will be easier to use an indicator as I said if you are not trying to clear the length of the threads. Basically go from the opposite side.
    Last edited by BigLakeBob; 07-27-2017 at 11:59 AM.
    Bob Rice #6738
    He that conquereth his own soul is greater than he who taketh a city.

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    Thanks Bob!

    My protractor lacks a tiny adjustable cross-slide rule like that. I was about ready to cut it up.

    I understand using the lathe postholder to read the angle, but you lost me with the 180 flip. Working in the open side of the nut seems easiest to me!

    ....Cotten
    Last edited by T. Cotten; 07-27-2017 at 12:24 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  10. #10
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    Quote Originally Posted by T. Cotten View Post
    It is easily accommodated if it can be accurately measured.
    Depending on what you consider "accurate," a set of angle plates might be all you need:

    http://chandcompany.com/insize/misce...s-4003-12.html

    They're the right size to insert in that nut and if the internal angle of the nut is the same as the plate the bottom surface of the plate will be parallel to the outside flat on the nut. Up to 5-deg. it only takes one plate, and beyond that two plates held together would give 1-deg. resolution.

    Of course, there are more accurate ways of making this measurement, some of which have been mentioned by others, but none are nearly as quick as using these angle plates. Again, whether these plates are accurate enough for what you need depends on what accuracy you need.

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