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Steel vs Mild Steel vs Stainless

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  • Steel vs Mild Steel vs Stainless

    I'm starting to shop for equipment to do a little sheet metal work to complement my other machine work and help with some projects associated with my "day job". Right now, I have a jones for bending brake and shear type machines, possibly a combination machine.

    These machines are normally speced by width and the gauge of metal they can handle. For example, they may say it's a 36" wide brake that can handle 18 gauge mild steel. I can understand that they might spec the gauge in the easiest material so it sounds like it can handle bigger stuff. My question is this:

    For the purpose of a bending brake and shear, how do steel, mild steel, stainless steel, and aluminum compare? Is there some kind of chart that shows that if you can handle 20 ga mild steel that you can therefore handle 16 ga aluminum, 24 ga stainless, and 21 ga "regular" steel? Thanks.

    -M
    The curse of having precise measuring tools is being able to actually see how imperfect everything is.

  • #2
    Way back when, I worked for a sheetmetal company. If I remember correctly, our shear was a 4ft shear and was rated for 16gauge mild steel. We didn't have a chart on the brake or shear giving anything other than the mild steel rating. I think the shear would handle 20 gauge stainless without having to overexert yourself on the step, but that was about the limit. We didn't do much aluminum work, but when we did, it cut like butter comapared to either of the steels.

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    • #3
      Stainless you usually de-rate the machine by 1/2. That's actual thickness not guage.

      Aluminum is either the same thickness or slightly more depending on alloy and temper.
      I just need one more tool,just one!

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      • #4
        Weird has it right IMHO

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        • #5
          Thanks, guys. Yeah, cntryboy and weird said about the same thing - 20 ga is a bit more than half the thickness of 16 ga. And unless you have some unusually tough al, my experience to date is that it *does* cut like butter

          It's just that stainless is so nice to work with - it's very tough, and even I can weld it...
          The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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          • #6
            FWIW, I have about the same experience with my Chiwanese combo. IE, 1mm mild steel, 0.6 316ss, 1.6 5000 series ali.
            Rgds, Lin

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            • #7
              Mild steel is regular steel.
              Unless you are talking about galvanized steel.
              The way most sheet metal machines are rated is for mild steel.
              So you need to figure if you can do 16 ga mild steel, you can do 18ga galvanized, and 20 ga stainless. Drop 2 ga for galvanized, and 4 for stainless, and you will be safe, especially for the import machines that are a little over optimistic in their ratings.
              But these are for full capacity materials- that is, a 4 foot 16 ga brake will bend a full 4 foot wide piece of 16 ga. So it will probably bend a 2 foot wide piece of 16 ga stainless. But it wont go a whole lot thicker- most 16 ga sheet metal tools will be damaged by much 14ga, and ruined if you dry to run 1/8" (11ga).
              There are a lot of 16ga tools out there- Tennsmith are a good brand of made in the USA tools, Chicago D&K are a better one. Then there are all those cheezy chinese imports.
              I would recommend getting a good book on sheetmetal, the one I always recommend to get started is Sheet Metal Shop Practice, by Leo Meyer, ATP books- you can often find it used on Abebooks.com or ebay, and it is the standard apprenticeship book for sheet metal unions, so it goes step by step thru measuring, layout, hand and machine tools, and how to do most basic sheet metal practices. It talks about metal gages, the differences between kinds of metals, and how to use a brake and shear and rolls.

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              • #8
                These types of machines are always rated with thickness to length ratios. If you want a true representation then you need to calculate the tonage. The calculations are in the handbook and are very simple.

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                • #9
                  <font face="Verdana, Arial" size="2">Originally posted by C. Tate:
                  These types of machines are always rated with thickness to length ratios. If you want a true representation then you need to calculate the tonage. The calculations are in the handbook and are very simple. </font>
                  Wow. Once again, you folks come through. I like Tate's answer the best, though. It almost sounds too good to be true, but it sounds reasonable. Intuitively, that's exactly what I would have thought, but I didn't know if there was something about stainless, for example, that could damage the blade on a shear or somehow screw up a brake if you exceed some thickness, regardless of the width. It's just that it seems machines that can handle, say, greater than 21-22 gage stainless start getting a bit pricey. And of course, I have a bit of 20 gauge lying around, and can get more pretty cheap or free. Sigh.

                  Oh yeah. And I probably will do some reading. Thanks, Ries.
                  -M


                  [This message has been edited by Wirecutter (edited 06-13-2005).]
                  The curse of having precise measuring tools is being able to actually see how imperfect everything is.

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                  • #10
                    personaly I would use stainless myself.
                    Thats just me though.

                    ------------------
                    All people need are rules
                    All people need are rules

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                    • #11
                      rigidity also counts, at least for the shear. Maybe consider old iron? mine, a great old boogs is 16 guage, cast throughout and weights about 800lbs - rock solid when you put some force to it, cost: $200 cdn. all the commercial places seem to have newer power stuff, so there must used shears out there
                      .

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