[TheForge] rigid vs. springy steel

[Andrew Vida]

Bruce - don't forget all the 1 1/2" hex that's under the crane at 
Marshall's.  It should be 9260 and it is brutally tough stuff.  A 6 or 8 
inch chunk should be more than enough.  Fire up the hammer and prepare 
for slow movement. :)

On 7/25/2013 3:12 PM, Jerry Frost wrote:
> You're on the right track Bruce, a little thicker and more tightly wound
> AND don't put a spring temper on it, only draw it back to medium to dark
> straw and you'll be good to go. Oh yeah, spring steel is a good choice
> as it's more forgiving in the heat treat so little differences in
> temperature don't have major effects.
>
> I guess I'll *never *learn and keep on replying before reading the whole
> post. <sigh>
>
> You're wanting to make a speed bar, great tools, I have a few though
> I've never made one. I'd forge it down from spring stock and temper it
> to medium straw. springs are typically drawn back (tempered) well into
> the blue. You'll want to make a couple test pieces (coupons) to get the
> temper right, they WILL be struck with hammers so do a few tests.
>
> A good alternate stock is found in tire irons, lug wrenches or (big
> surprise!) pry bars, yard/garage sale stuff. Again, make some test
> coupons as a departure point I'd draw the temper down to the straw and
> adjust from there depending on the test coupons.
>
> Jer
>
>
> On 7/25/2013 1:06 AM, Bruce . wrote:
>> Here's a question you metal munchers might be able to field:
>>
>> I have had a few applications in which I need thin but rigid steel.
>> What steel is best?
>>
>> Consider for example a corkscrew -- it's a helix that holds its shape,
>> it's rigid. But a spring with a comparable shape is flexible. What's
>> the difference? I suspect that it's simply the relative dimensions --
>> a spring is relatively thinner wire wrapped on a relatively larger
>> mandrel, and vise-verse the corkscrew.
>>
>> But is that all there is too it, or is there a metallurgical
>> difference as well?
>>
>> Although I've contemplated making corkscrews, the immediate
>> application is a prybar for roofing and siding nails and similar
>> stuff. It would be flat, like these:
>> http://www.homedepot.com/p/Dasco-Pro-Pry-Bar-Set-3-Piece-91/202585548#.UfDoym1cWgw
>>
>> but of thinner steel. (If I can't make it thinner, I'll just use a
>> commercial one.)
>>
>> I'd like it as thin as possible for a number of reasons, but I don't
>> want more than minimal flex to the thing. So I'm wondering what steel
>> to use.
>>
>> I have, BTW, considered using thin steel and putting longitudinal
>> bends ("ribs" or "nerves" or "corrugations" -- whatever you want to
>> call them -- as are used in larger HVAC ducts to prevent oilcanning of
>> the large flats) in it, but this partially defeats the purpose, as the
>> result would effectively be thicker -- so why not use thicker metal
>> and be done with it?
>>
>> This is not any sort of critical problem, but I've had similar
>> problems before and left them unaddressed. This time I thought I'd
>> ask....
>>
>
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