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Degradation of Steel Due to Punctures

  1. Aug 17, 2013 #1
    Hello everyone obviously smarter than I. There is an answer I seek, to a project that is willing to be done.

    I'm considering manufacturing a piece of fitness strengthening equipment that is somewhat unique. There is some sort of equation I'm missing to have an understanding of how to go about the construction, ie which materials to use, and what their capabilities will be.

    I'm trying to make equipment that is variable in height and length. Without giving away the design, I can say that my need to know revolves around understanding how drilling holes into steel bar/or pipe will degrade said piece.

    I'm also interested if this degradation in structural integrity and accompanying strength would be offset by filling it snug with a steel bolt of the same quality.

    An example would be a piece of steel with the strength to handle 1,000 lbs attached to it. Now take a piece of this steel that is circular of 1" OD, and insert a piece that is 17/16 ID. Fit the same holes of 1/4" drilled into each side of each piece, and a 1/4 bolt fitted through all 4 holes. Would it still hold 1,000lbs, IF the bolt was rated for 1,000#'s.

    Now to add to the mix a few more holes punched every inch running the length of the pipe in a line, which aren't filled with bolts running along the sides of both pipes. Essentially to make the length and/or height of the equipment variable. Would it then be unable to hold the same 1,000# at this point?

    To what degree would their be loss in strength?
    Is there a simple equation I can plug in, or would this depend on the overall structure of said equipment? I need to keep it as simple as possible, so let's not envision the whole object (as you have no idea what it is!) and just keep the physics to two pieces of pipe one fitting inside the next snug.

    Please let me know if further clarification is needed. Thanks.
  2. jcsd
  3. Aug 18, 2013 #2


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    You can't design this type of equipment with a single equation. Because it is fitness equipment, and there are potential liability issues involved, I would urge you to seek the advice of a mechanical engineer, if nothing else for your own protection.
  4. Aug 18, 2013 #3
    If that equation would let me know the absolute stength of the pipe, I sure can! This isn't complicated, and I'm not going to get sued if it doesn't snap. Easiest way would be trial and error. Load the equipment with a lot of weight and run it through some tests. If it snaps I know to try something different. I can rig up something to test it somewhat safely.
  5. Aug 18, 2013 #4


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    That's just it: there is NO single equation which will allow you to design this equipment to be safe, and certainly not one which can be applied to a design which can only be vaguely described. Any time you punch a hole in something, there will be a loss in strength. The knowledge and skill which allow the safe design of machines are not such that they can be picked up in a couple of posts on a blog somewhere.
  6. Aug 18, 2013 #5


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    I think that is a bit of overconfidence. Japan never expected a crisis with its nuclear plants nor did Mcdonalds ever expect to be sued over a cup of coffee. It is not your design process I am commenting upon, just that one very erroneous statement.
  7. Aug 18, 2013 #6
    Now coffee is something dangerous!

    Seriously. Incredible over thinking here.

    You know why mcdonalds got sued? They didn't have a disclaimer. My products will have disclaimer. I'm not an idiot. Squat racks have the same damned thing and are often design to hold more weight than what my product will.

    Oh, and Fukushima should never have been built. So many design faults, but that's a whole other topic. It's like saying, "nobody could have foreseen the economic downturn". Inevitable to all but the mindless.
  8. Aug 18, 2013 #7
    This is seriously ridiculous. Why do I have to tell you of every component involved? All I need to know is the extent which a single piece will be degraded by punching some holes in it. You want specifics then ask else I don't know what to provide for you. You want safety in a strength conditioning device? Don't bother getting out of bed. You might just slip and break an ankle.

    Completely ridiculous. I'll find help from more reasonable people who have a little common sense.
  9. Aug 18, 2013 #8

    Vanadium 50

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    Thread closed. The OP has his answer. The fact that he doesn't like it doesn't change the fact that that's the answer.

    OP, you might want to look up "Arthur Jell" when you think about safety.
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