A question re: steel - hot rolled vs cold rolled

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  • BrianY
    Left Wing Extremist
    • Apr 2004
    • 7942

    A question re: steel - hot rolled vs cold rolled

    I'm building a thickness sander and I need to purchase a steel rod to serve as the shaft for the drum. I can buy hot rolled or cold rolled steel rod in the size I need...but I don't know nothin about the different types of steel and why I should prefer one type over the other. Any advice will be appreciated.

    In case it matters, the shaft will be 5/8" dia. X 18" or 24" long (haven't decided on that yet). The drum will be made of 5" dia. MDF disks.
    I rather be an American than a Republican.
  • MiddleAgesMan
    Senior Member
    • Jul 2007
    • 6677

    #2
    Re: A question re: steel - hot rolled vs cold rolled

    For a rod, cold-rolled is better--stronger and probably more precise in size.
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    Comment

    • Hugh Conway
      Banned
      • Jan 2012
      • 9162

      #3
      Re: A question re: steel - hot rolled vs cold rolled

      as sold by metals shops near me:
      hot rolled - cheaper, looser tolerances, more mill scale (which is a pain to remove) on the top
      cold rolled - more expensive, tighter tolerances

      curious what plans you are using to make the thickness sander, it's on the list of things to investigate.

      Comment

      • Canoeyawl
        .
        • Jun 2003
        • 37698

        #4
        Re: A question re: steel - hot rolled vs cold rolled

        Hot rolled and cold rolled mild steel will be the same alloy
        Cold rolled will be +.000 -.002 tolerance
        Hot rolled will be no where near that.
        Mcmaster Carr sells small quantities of various alloys with an introduction explaining the properties of the various alloys they sell.
        You may want a better alloy than mild steel.
        try this page http://www.mcmaster.com/#about-carbon-steel/=ncsodm

        edit to add; I have repaired broken spindles in thickness sanders, they suffer from fatique (work hardening) at the drum/shaft connect

        Comment

        • BrianW
          not your average member
          • Nov 2002
          • 28191

          #5
          Re: A question re: steel - hot rolled vs cold rolled

          Cool project.

          Is it like this one?..



          “Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.”― Mark Twain,

          Comment

          • Nicholas Scheuer
            Senior Member
            • Aug 2006
            • 13579

            #6
            Re: A question re: steel - hot rolled vs cold rolled

            Cold Rolled would be what you'd want for the axle of a kid's wagon. Hot Rolled is like rebar for concrete. The grain in cold rolled has been elongated by the process and is stiffer and stronger, given the particular alloy elements.

            Comment

            • Keith Wilson
              Trying to be reasonable
              • Oct 1999
              • 64114

              #7
              Re: A question re: steel - hot rolled vs cold rolled

              The major difference in ordinary low-carbon steel is surface finish, size tolerance, and cost, although neither are very expensive. Strength is roughly equivalent. Stiffness is identical for just about every type of steel, no matter how fancy. I'd buy cold-rolled. If you're concerned about strength it would probably be more economical to just make it a larger diameter than to buy more expensive steel.
              "For a successful technology, reality must take precedence over public relations,
              for nature cannot be fooled."

              Richard Feynman

              Comment

              • BrianY
                Left Wing Extremist
                • Apr 2004
                • 7942

                #8
                Re: A question re: steel - hot rolled vs cold rolled

                Originally posted by BrianW
                Cool project.

                Is it like this one?..



                Yes pretty much. I haven;t seen that one before so thanks for posting it. He's got some interesting ideas that are worth considering for my own build.
                I rather be an American than a Republican.

                Comment

                • Canoez
                  Did I say that out loud?
                  • Sep 2007
                  • 20611

                  #9
                  Re: A question re: steel - hot rolled vs cold rolled

                  Originally posted by BrianY
                  Yes pretty much. I haven;t seen that one before so thanks for posting it. He's got some interesting ideas that are worth considering for my own build.
                  If you're looking for precision - don't forget to consider ground rod stock - it's available with a variety of ends - male thread, female thread, reduced diameter, soft ends for machining, etc.
                  "The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
                  -William A. Ward

                  Comment

                  • wardd
                    Senior Member
                    • Sep 2009
                    • 15162

                    #10
                    Re: A question re: steel - hot rolled vs cold rolled

                    you can buy shafting with key way

                    Comment

                    • Canoez
                      Did I say that out loud?
                      • Sep 2007
                      • 20611

                      #11
                      Re: A question re: steel - hot rolled vs cold rolled

                      Originally posted by wardd
                      you can buy shafting with key way
                      Yes.
                      "The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
                      -William A. Ward

                      Comment

                      • BrianW
                        not your average member
                        • Nov 2002
                        • 28191

                        #12
                        Re: A question re: steel - hot rolled vs cold rolled

                        I guessing the only reason for using solid rod, instead of tubing, is for the key way?

                        Tubing would be lighter and more resistant to bending.
                        “Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome, charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime.”― Mark Twain,

                        Comment

                        • Keith Wilson
                          Trying to be reasonable
                          • Oct 1999
                          • 64114

                          #13
                          Re: A question re: steel - hot rolled vs cold rolled

                          Tubing would be lighter and more resistant to bending.
                          For a given diameter, a solid shaft is a bit stiffer. For a given weight, a tube is stiffer. You can put a keyway in a hollow shaft if the wall is thick enough.

                          If you're putting the shaft into mounted bearings (pillow blocks or flange bearings) you can get the shaft tolerance from the bearing manufacturer. Normal spec for a 5/8" shaft is +0, -0.0005" (yeah, that's half a thousandth) although you can get by with a somewhat sloppier fit if shaft runout isn't critical. Normal tolerance on 1018 cold-rolled bar is +0, -.002, which should be fine for this application.
                          Last edited by Keith Wilson; 06-26-2013, 01:10 PM.
                          "For a successful technology, reality must take precedence over public relations,
                          for nature cannot be fooled."

                          Richard Feynman

                          Comment

                          • wardd
                            Senior Member
                            • Sep 2009
                            • 15162

                            #14
                            Re: A question re: steel - hot rolled vs cold rolled

                            Originally posted by Keith Wilson
                            For a given diameter, a solid shaft is a bit stiffer. For a given weight, a tube is stiffer. You can put a keyway in a hollow shaft if the wall is thick enough.
                            the key ways would have to be milled only where needed on a tube which would require machine shop work

                            for his application a 1" shaft at most a foot long or so would not be that much weight

                            it's a piece of shop equipment not an airplane

                            Comment

                            • Canoeyawl
                              .
                              • Jun 2003
                              • 37698

                              #15
                              Re: A question re: steel - hot rolled vs cold rolled

                              For that application, a steel that will bend or flex through more cycles would be the deciding factor for me.

                              I spend a lot of time (and other peoples money) repairing machines that have failed due to fatique from cyclic stress.

                              One in particular is a certain thickness sander. The part itself is too expensive for me to manufacture versus the cost of replacing it with another "over the counter part". But if I was starting from scratch I would consider a better alloy than mild steel.

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