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Ed Huntress
 
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"Dan Miller" wrote in message
news In answer to Ed's question I generally make tools. I get a lot of flack from
my wife and friends about using tools to make tools to make tools. (right
now I'm making a ball turning tool to make handles for tools) Anyway, they
see it as circular...I see it as fun.

Anyway, I want them to look nice as well as be functional and being a
relative novice at the lathe (I don't have a milling machine) I spend a lot
of time trying to find the right grind for the bits, the right speed etc to
get a nce finish. I used to buy all my steel from this steel salvage yard
near where I live but then realized that I know little about the alloys I'm
picking up. the Shape and size selection is great though. I stumbled across
a few pieces that machined really nicely and that got me interested. Now I
buy the stuff from a local online place and that way I get the exact size,
length, and alloy I want....something to be said for that.As far as steel
goes they sell 12L14, 1018, and 4130.

Lots of the stuff I make is threaded, and sometimes I make the nuts etc.
I've had little experience with the 12L14, sounds like strength-wise it is
fine. I worry about wrenches and stuff chewing it up if I make nuts with it
but perhaps this is unfounded as well. Is it noticeably less stiff than
1018? Maybe I'll just stick with it. Is there ever a case where 1018 is
preferable?
========================

Regarding stiffness, all steel is almost equally stiff. There is a common
misconception that stronger steel is stiffer (has a higher modulus of
elasticity, or Young's Modulus). 'Tain't so. Stainless is slightly less
stiff than carbon steel, but all carbon steels and nearly all alloy steels
fall into a range of about +/- 6% on stiffness, regardless of heat treatment
or work-hardening.

As for strength, 12L14 has roughly the same strength as other low-carbon
steels. Its elongation (a measure of its ductility) is not bad; within the
range of other steels of comparable strength. If you want to use it for
general-purpose toolmaking and parts-making, check on how it welds, brazes,
solders, and case-hardens. I used to know but I forget. The info is readily
available.

1018 is fairly easy to machine and it welds very easily, brazes very easily,
solders very easily, and it's easy to case-harden. I find that cold-rolled
1018 and 1020 are easier to machine than annealed- or hot-rolled steel in
those grades, but I'm not very good at getting good finishes on steel of any
grade. g Except for 12L14. I've only used it a couple of times but it does
machine and finish very nicely.

4130 is a tough, shock-resistant steel of medium strength that has good
elongation for its strength, and that welds very well. It's no stiffer than
other grades of steel. It was designed originally for aircraft applications,
back in the 1920s, and it was specifically alloyed for making safe, reliable
welds in a steel with roughly twice the strength of low-carbon steels. It
makes very good tubing for airframes. You can weld it with O/A and all
electrical methods. It offers no particular advantage for making tools, with
rare exceptions. It ain't cheap. You may find occassional use for it in
making highly-loaded shafts and other stressed mechanical parts.

Those three steels available from your supplier should meet most of your
needs, but I would add one other grade for the home shop: 1070, or something
thereabouts. You may need to make something that you can heat-treat into a
hard or strong condition, and a plain-carbon steel in the range of 1070 -
1095 is a lot easier to heat-treat with basic equipment than most of the
alloy steels are.

--
Ed Huntress