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. 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