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Help with deflection/safe load

  1. Oct 14, 2014 #1
    Hey everyone,

    I am not a structural engineer; so I thought maybe I could get some help understanding the concepts of a project I am trying to complete. I am trying to get a rough estimate of a safe load capacity for a "lifting bar" .

    The material itself is 1" diameter x 36" long 1045 steel bar. A lifting D- Ring will be centered on this bar as a lifting point.

    Every equation that I have looked into shows deflection of beams supported at two ends with the load in the center...... What is the appropriate way to determine how much load can safely be hoisted......Loads on the ends of the beam with a suspended center point V----------^----------V ??

    Any help would be appreciated....want this to be as safe as possible
     
  2. jcsd
  3. Oct 14, 2014 #2
    Turn your reference up side down. With that,the upward force is in the center, and the downward forces are at the ends.
     
  4. Oct 14, 2014 #3
    Thank you.. I pondered over that... but is it in fact the same? Because the center lift point theoretically isnt applying an upward force..the two sides are just applying downward force on a center supported object? Or is it and I am over thinking it?
     
  5. Oct 14, 2014 #4

    berkeman

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    Staff: Mentor

    Welcome to the PF.

    Can you say more about your project? What will you be lifting? Is this project for schoolwork, or a personal project? If it is for schoolwork, do you have an adviser that you can talk this through with?
     
  6. Oct 14, 2014 #5
    Hey Berkeman; this is a personal project....unfortunately I have no adviser at my side :) ..... This is going to be used for lifting granite...I will have a steel shaft suspended from a center lifting point....on this shaft will be rollers. They make these to buy...but I wanted to make my own; but I do need it to be safe....for my personal safety and for the liability of the merchandise in the air. I am using the same material that is used in the production models you can buy with slight differences.... I just want to learn how to do the math for my own benefit.
     
  7. Oct 14, 2014 #6

    berkeman

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    Staff: Mentor

    That's the issue that I have with this thread. We don't allow discussion of dangerous activities here, and helping you analyze the safety of a mechanical lifting device (when you have no experience or training in that analysis and math) could be a bad idea. I've asked for the opinions of the other Mentors. I'll temporarily close this thread until we can decide how to handle it.
     
  8. Oct 15, 2014 #7

    berkeman

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    Staff: Mentor

    After a Mentor discussion, this thread will remain closed. Please consider investing in the off-the-shelf solution.
     
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