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  • stress relieving cold rolled

    Just something I thought of today before I woke up. I recall my first experience with cutting square cold rolled. The piece splayed unbelievably, and from there I was introduced to the phenomenon of internal stress. A person could always heat the part to relieve stress before trying to cut it into some shape. What I'm wondering is how that would affect the square shape- it would likely not be square after that, is what I'm assuming. And it may not be straight either. What happens if you try to square it up again before cutting out your part- will it still warp and twist on you? Any thoughts on this, any guidelines as to choice of material for when you need to bandsaw a shape out of raw material?
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    the stresses are concentrated on the outside layer, so you can machine them away - but you've got to think through the clamping and sequence. Once the thing is warped and twisted, and the outer layers are removed, you’ve to create a reference surface and then start squaring it up.

    I’ve had cold rolled normalized or stress relieved and comes back looking much like hot rolled, although iirc it comes back pretty much in the same shape that it left in – ie the treatment seemed to let out the stress without warping and twisting the material. I sent it out because I wanted it dead on and I think you have to hold at heat for a while – not a problem if you have a furnace.

    Once its been normalized it should be stable. as far as how square and straight it is, i my limited experiece I'd say its no worse than other raw bar stock - but you'd have to put some numbers around it - ie what's square and straight?
    .

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    • #3
      What's square and straight? Visually straight would be good enough I suppose, and square enough to not rock on the mill table when clamped for machining. I don't want to bother with annealing, since if I needed to cut a shape out of existing stock, I'd want to choose the material first to be suitable. From my experience, cold rolled is best used when the cross section doesn't have to change. Cut to a length, fine. Drill some holes, fine. Mill a groove out of one side, or cut say an L shape out of it- not so fine. Part of my question is what material would I ask for at my local metal shop to get a fairly accurate square or rectangular cross section, and be free from warping when cut into- I'd be using 1/2 x 1 for instance, or 1 x 1, or 1 x 2 typically. Not looking for any special or expensive steel, just something they would likely have on hand.
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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