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Thread: Screws or bolts?

  1. #36
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    Default Re: Screws or bolts?

    I'm sure they are in a hole large enough to just push them in or out with your finger. All you need is the friction of the mating surfaces to hold it together!

  2. #37
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    Default Re: Screws or bolts?

    Quote Originally Posted by Peerie Maa View Post
    Ever tried getting one of them out? What weight of hammer did you have to use to drive it back out?
    So far I've only popped off the two fifty-pound deck cleats up forward. The bolts tapped right out. Hefty backing plate below doing the compression.

    Quote Originally Posted by canoeyawl
    I'm sure they are in a hole large enough to just push them in or out with your finger. All you need is the friction of the mating surfaces to hold it together!
    Take a class in mechanical engineering. There's some non-obvious stuff in there.

  3. #38
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    Default Re: Screws or bolts?

    Quote Originally Posted by Favorite View Post


    Take a class in mechanical engineering. There's some non-obvious stuff in there.
    Maybe they will start with something simple like lugnuts?

  4. #39
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    Default Re: Screws or bolts?

    Quote Originally Posted by Favorite View Post
    So far I've only popped off the two fifty-pound deck cleats up forward. The bolts tapped right out. Hefty backing plate below doing the compression.


    Take a class in mechanical engineering. There's some non-obvious stuff in there.
    I did, as a part of my BSc in Naval Architecture.

    There is a significant difference between bolting a deck fitting down and uniting structural components.
    It really is quite difficult to build an ugly wooden boat.

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  5. #40
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    Default Re: Screws or bolts?

    Slip critical fasteners on wooden structures seems like poor engineering to me. I always strive for bearing type fasteners and if I can't incorporate them I redesign.

  6. #41
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    Default Re: Screws or bolts?

    Quote Originally Posted by Peerie Maa View Post
    There is a significant difference between bolting a deck fitting down and uniting structural components.
    But the question was about dudgeons and pinballs, not frames to keels. Pintles look like a perfect place for bolts to me - sandwich the wood between two arms of bronze and clamp away to your heart's content. Spread the load over a large surface rather than put a couple of nails in shear with high and very localized stresses.

    I guess canoeyawl doesn't trust the heads to stay on his engines or the caps to stay on his rods, either

    Agreed tho, that crush strength is a problem and bolts are not suitable for many places in wood. But where they do work, using them like nails with threads on the end seems rather pointless to me. They are intended to work in a different way.

  7. #42
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    Default Re: Screws or bolts?

    Quote Originally Posted by Canoeyawl View Post
    Maybe they will start with something simple like lugnuts?
    Lugnuts are not in shear. They are in tension.

    As I said, take an introductory class in mechanical engineering.

  8. #43
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    Default Re: Screws or bolts?

    Quote Originally Posted by Favorite View Post
    Lugnuts are not in shear. They are in tension.

    Wouldn't acceleration and braking introduce a sheer force?

    Just tryna learn here.

    Jim

  9. #44
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    Default Re: Screws or bolts?

    Quote Originally Posted by Favorite View Post
    But the question was about dudgeons and pinballs, not frames to keels. Pintles look like a perfect place for bolts to me - sandwich the wood between two arms of bronze and clamp away to your heart's content. Spread the load over a large surface rather than put a couple of nails in shear with high and very localized stresses.

    I guess canoeyawl doesn't trust the heads to stay on his engines or the caps to stay on his rods, either

    Agreed tho, that crush strength is a problem and bolts are not suitable for many places in wood. But where they do work, using them like nails with threads on the end seems rather pointless to me. They are intended to work in a different way.
    Two of us have already suggested that the most elegant least clunky solution is to rivet over copper rod into countersinks in the straps that are to be fabricated for the gudgeons and pintles on the rudder blade. Coach bolts will be best through the transom with big backing plates on the inside under the nuts.
    It really is quite difficult to build an ugly wooden boat.

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  10. #45
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    Default Re: Screws or bolts?

    Quote Originally Posted by Favorite View Post
    Lugnuts are not in shear. They are in tension.

    As I said, take an introductory class in mechanical engineering.
    I guess that (bearing) tapered bit is not important?

    Asfar as heads and connecting rods go, both have other means of accurate location, and are not shear critical.
    Arguing about the differences in clamping forces of those compared to wooden structures is, well... silly
    Last edited by Canoeyawl; 01-17-2019 at 03:03 PM.

  11. #46
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    Default Re: Screws or bolts?

    Quote Originally Posted by Jim Ledger View Post
    Wouldn't acceleration and braking introduce a sheer force?
    The fasteners are never supposed to see that. The clamping force is supposed to always be higher than any other forces, so that the bolts only see tension. The compression / friction forces of the clamped joint should always be higher than any other forces the joint will see. Therefore, the fasteners are never in sheer and don't get fatigue failures, either.

    The tapered seats in wheels are just for centering the wheel. That's ALL they do.

    And the left-hand threads on Chrysler cars were silly

    Next week we can attack the "stronger steel is more rigid" myth

  12. #47
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    Default Re: Screws or bolts?

    The question is;
    Are the bolts (capscrews, lugnuts, etc) "bearing" or are they "slip critical"?

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