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  • Re: Which steel rod would have the least sag/twist/flex of a 4' stretch

    From Clare Snyder@21:1/5 to [email protected] on Thu Dec 7 16:52:33 2023
    On Thu, 7 Dec 2023 04:08:04 -0800 (PST), SCORELINK Limited
    <[email protected]> wrote:

    Hi Carl!

    Wow, great information -- I'm a biologist so this engineering is fascinating but elusive to me!

    We have a similar problem, and I was wondering if you could lend your expertise:

    We have a 1inch tube (25.4x3mm) at 3000mm length. It currently "sags" and we need to improve its rigidity. We can changer the diameter if needed, but I'm looking for a steer on what would be the best way to ensure high levels of rigidity over that
    distance, either tube or rod. any thoughts?

    Many thanks in advance
    1 inch X5/16 wall DOM tubing would be one of the best solutions if
    you need to stay with one inch. 1 inch by 1/4 wall 4130 electric
    welded tubing will likely be about the same price - trading off mild
    steel for alloy vd the extra cost of mandrel drawn (which you don't
    need the bore accuracy of). - or if you can go larger go to 1 1/2
    inch 4130 or 1 1/4 inch DOM. Tubing has better bens strength than bar
    stock and weighs a bit less - contributing less to the sag - - -

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  • From Richard Smith@21:1/5 to All on Sun Dec 10 06:48:19 2023
    As Jim and others say:
    number-one approach - increase the diameter.

    I'll add a complimentary comment.
    Does the section have to resist local buckling?
    This is a crucial issue in engineering.
    Sometimes with something like an aeroplane weight it crucial and you
    have to accept structures where if they buckle "that's it" - they are
    finished.
    For buildings and static steel structures you aften ensure that the
    sections will keep "distributed" bending and will never buckle.

    You will have to look-up about this.
    For commercial steel sections it's the "Class" of a section.

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