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Cast iron table top warped? How?

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  • Cast iron table top warped? How?

    So just how does a cast iron table top get warped. It is pretty darn heavy and kind of thick with webbing underneath. You are not jumping up and down on it. Wood doesn't weight that much. It doesn't seem to get hot. Does anyone know how this can happen? Just curious.


  • #2
    If machining is done too soon after the iron is cast it can warp. It needs to be properly aged and stored so that internal molecular stresses are settled. I'm not sure if that is what has happened in this case, but I do know that in the heavy compressor plant that I worked for thirty years, the there was a lengthy time period given to castings after they came out of our foundry. Of course those were much heavier castings compared to what a saw table top requires, but I believe similar stresses would come into play.



    • #3
      It might also occur because of improper storage. I've heard of cast parts for equipment that are machined to provide a mating or sealing surface becoming distorted due to improper storage.

      IIRC you bought this saw used, and are (at least) the third owner. So you don't know how the first two treated it.

      Maybe the saw sat in a unconditioned garage for a while with something heavy like a toolbox sitting in the middle of the table. And over time in the heat of summer the CI table top deflected due to the weight placed on the unsupported area of the table. It doesn't take years for this to occur.

      Rather than using a straight edge of a level (which may not be true), try stretching a string diagonally from corner to corner and measure the deflection. Do the same in the other direction, and take two more readings so you have observed the string ever 45 degrees. If the table is high in the center then use a pair of equal thickness shims, one at each edge of the table to raise the string above the high spot slightly and measure.
      Last edited by Bob D.; 03-13-2020, 04:28 AM.
      "It's a table saw, do you know where your fingers are?" Bob D. 2006



      • #4
        True I don't know what it has been through. Just would not have thought that would be the problem here. But you live and learn everyday. If you are lucky. The table was warped down from the miter slots to the center of the table insert. The was using a certified 18" straight edge.