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Leveling a hanging surface

  1. Mar 3, 2012 #1
    If I have a tabletop, and I can hang it from above with rope, is there a way I could hang it so that it would be necessarily level? It has legs attached and the mass is not necessarily distributed evenly relative to the flat surface of the table.

    I imagine this is probably not the best way to make a level table, but I was just thinking about it and wondering if this would work. To actually finish the table I would have the table hanging such that each leg was in a bucket (but not touching the bottom so the table is still hanging free), and once I had it hanging correctly I would poor concrete in each bucket.

    My thought was to attach four equal lengths of rope, one to each corner, and then connect them together to a central rope.
     
  2. jcsd
  3. Mar 3, 2012 #2

    DaveC426913

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    Trying to hang it would be a bad idea. It's too prone to shifting, especially over the time it takes for concrete to dry.

    Why wouldn't you support it with temporary legs from below?
     
  4. Mar 4, 2012 #3
    With the table made level by the 'hanging rope method' and the legs in the bucket into which concrete would be poured and let to set for an amount of time, after which the ropes are removed, and the table should now still be level, is a misconception as one has to assume that each leg will now bear one fourth of the table weight, again from another assumption that the table weight is evenly distributed, and that the compression of each leg is also proportional to one fourth od the table weight, again from an assumption that each leg is completely similar to all the other three.

    In addition, there will be an air space under leg between the bottom of the leg and the concrete and one has no way of knowing how large this air space will be or if the air space has been completely eliminated with agitation of the concerete before it has set, with the ensuing result that some legs may rest on more or less concrete whose compression from the table leg can thus not be determined beforehand.

    I would conclude that this method would result in a table that is nearly level, with no method of determining how near to level the table would be.
     
  5. Mar 4, 2012 #4

    DaveC426913

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    I don't follow how the weight of the table or distribution or size of each leg would affect this. If he manages to level the tabletop, and sets the concrete. What's the problem?

    You'd use a level on the table top.
     
  6. Mar 4, 2012 #5

    jim hardy

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    Rope stretches.

    Use a machinist's level and shims.
     
  7. Mar 4, 2012 #6
    Simple stress strain of materials.
    Once the ropes are removed, the legs are now bearing the weight of the table where they had not before. As I had said, the table will in the end should be nearly level, and probabably level enough for most purposes.
     
  8. Mar 4, 2012 #7
    My main question is if it would be possible to go about leveling the surface in the first place. Would my described method work, with a rope attached to each corner attached to a central rope?

    I'm okay with assuming the rope doesn't stretch.
     
  9. Mar 4, 2012 #8

    DaveC426913

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    It would be possible, yes. But a better question is: would it be practical.
     
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