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Thread: How Many Threads?

  1. #1

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    How Many Threads?

    Eavesdropping on a hangar conversation, a discussion of proper length of prop bolts showing at the other end---one says one-sixteenth of an inch, the other a thread or two. Offers? Thanks

  2. #2
    mike mcs repair's Avatar
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    'threads showing at the other end' do nothing.... flush or a mile, all hold the same....

  3. #3
    Anne's Avatar
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    Two threads, but I'm not sure if that's for all bolts, or certain ones. That's what it was when I added shoulder harnesses and used the brackets from Atlee Dodge. Maybe it depends on the diameter of the bolt, or what it's holding together.
    Baloney is still baloney, no matter how thin you slice it.

  4. #4
    8GCBC's Avatar
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    Propeller bolts.. Get data from manufacturer if possible. Off the cuff engineering... no more than a standard washer or two.

    Some manufacturers use bolt stretch for proper torque. This ensures a certain limiting smaller diameter of the bolt, which is more accurate than a torqure wrench.

  5. #5
    Bonanza32GF's Avatar
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    Mike, you have it right!

  6. #6
    8GCBC's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    'threads showing at the other end' do nothing.... flush or a mile, all hold the same....
    Correct! *Edit
    Last edited by 8GCBC; 04-29-2012 at 04:23 AM. Reason: Confusing statement

  7. #7
    mike mcs repair's Avatar
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    Quote Originally Posted by 8GCBC View Post
    NEED some threads under a washer for strech of the bolt. If no threads are showing you will be threading the bolt after it stretches!

    Everybody I know calls for some threads and a warsher. C'mon guys.
    you are confused.. again..

  8. #8
    8GCBC's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    you are confused.. again..
    Mike, how do you turn a nut with no threads?

  9. #9
    cgoldy's Avatar
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    Quote Originally Posted by 8GCBC View Post
    NEED some threads under a washer for strech of the bolt. If no threads are showing you will be threading the bolt after it stretches!

    Everybody I know calls for some threads and a warsher. C'mon guys.
    You will have to explain this one to me in plain simple English .

  10. #10
    8GCBC's Avatar
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    Quote Originally Posted by cgoldy View Post
    you will have to explain this one to me in plain simple english .
    OK... I stepped in it.

    I was thinking threads after washer installed (or under washer). Mike was saying before washer, which make more sense.

    Yes my statement sounded wrong and was confusing. Thank you for the correct statement MIKE!

    Hope SJ does not cut my bandwidth again
    Last edited by 8GCBC; 04-29-2012 at 04:18 AM.

  11. #11
    Steve Pierce's Avatar
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    Look at the amount of threads on the back side of the prop flange bushing and then measure the amount of threads on the bolt. This picture was posted on http://www.shortwingpipers.org/forum...3085#post53085 where the bolts were found bottomed out on the prop flange bushings and allowed the prop to fret on the crank flange due to not enough torque to hold the prop on.

    Prop bolt on the left, AN bolt that was holding the prop on right. Notice the amount of threads.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  12. #12
    cubunltd's Avatar
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    If the end of the bolt is square(threads all the way to the end), then the bolt has to be at least flush with the nut. If the end of the bolt gas a slight taper at the end then the taper has to protrude past the nut to the first thread. Most stretch bolts are used in the auto industry. I don't know of any that are used on aircraft except in some of the engines.

    John

  13. #13
    mike mcs repair's Avatar
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    Quote Originally Posted by 8GCBC View Post
    OK... I stepped in it.

    I was thinking threads after washer installed (or under washer). Mike was saying before washer, which make more sense.

    Yes my statement sounded wrong and was confusing. Thank you for the correct statement MIKE!

    Hope SJ does not cut my bandwidth again
    you are still confused the original post is asking how much sticks out the BACK side of prop flange nuts.......

  14. #14
    8GCBC's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    you are still confused the original post is asking how much sticks out the BACK side of prop flange nuts.......

    Damn. I really need to learn to read. It was really late last night.
    Last edited by 8GCBC; 04-29-2012 at 10:36 AM.

  15. #15
    8GCBC's Avatar
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    My uber cub buddies... I understand this...

    If possiblity that the bolt grip bottoms out in the flange bushing, result would be a loose propeller. Bolt must NOT bottom out in propeller mounting flange. Measuring the bolt and thread is paramount to ensure proper bolt tension. Bolt threads must fill entire length of bushing for strength.

    The amount of threads showing on the nut/clevis pin side should be about zero to provide proper grip length.

    Hoping I show some improvement?

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