Steel By The Numbers


Click here or on the photo for a PDF file.

Everyone knows about “cold rolled” and “stainless” steel. When you want something else you need to order steel by the numbers. 4140, 1215, etc steel. The steel industry uses a standard set of number to tell you all about the properties of a chunk of steel. How hard it is, tensile strength, easy or hard to machine, etc.

When I am looking around on the McMaster-Carr web site (www.mcmaster.com) for a nice piece of steel. The web site sometimes shows me a nice table that does a great job summarizing the different kinds of steel. (See above photo and PDF.) Other times I can get the web site to show me this table to save my life. I forget I need to search on “about steel” or “about tool steel”.

Steels I Use


I generally used “cold rolled” steel from my local steel supplier. They have a “cut offs” area where I can purchase cold rolled steel for $1 per pound.

I avoid “stainless” steel like the plague. Stainless can NOT be cut, drilled or welded with run of the mill metal working tools. It is just way to hard. Hack saw blades and drill bits just barely scratch the surface. I think manufactures (like the carbide tool manufactures) make tool shafts, etc out of stainless steel so you can not easily make a copy of their tools.

Cold rolled steel will rust. If exposed to a lot of water (if left out in the rain) but I don’t have much trouble with it rusting in my studio. When used for tool shafts, etc it develops a patina that stops it from rusting. You just need a little WD40 to stop it rusting from the start and then a little more WD40 here and there. Your mileage may vary.

When I want some steel with a nicer smooth finish for tool shafts, etc I use 4140 or 1215 steel. What you get from suppliers like McMaster, etc varies. 4140 (or 4130) is “Chrome Moly” steel. If often comes with a nice silver shinny surface. But not always. 1215 is similar, but easier to machine (cut and drill). 4140 is a little more difficult to cut and drill than “cold rolled” but it is doable with run of the mill metal working tools.

O1 tool steel (aka drill rods) are not to hard. You can cut and drill them. Otherwise, most of the other tool steels (M2, A2) are way to hard to deal with. You can cut them with a cut off wheel in a 4″ angle grinder. But, you can not cut them with a hack saw or drill into them. O1 is way to expensive in rectangular steel. I use rectangular 4140 or 1215.

Beware of steel rod tolerances. They are typically +/- 0.xxx” to 0.yyy”. They are almost always on the + side. Thus, If you order a 3/4″ steel rod and you want it to fit in a dead on 3/4″ hole it probably will not fit. The rod will probably be to big. Dead on holes are created in the metal working world by drilling a hole that is little less than the desired size and then “reaming” the hole to the desired size. It is the way things are suppose to be done in the metal world. You may have to bite the bullet and pay for a piece of “Tight-Tolerance” steel. They are often +/- 0.00x” to 0″.

Holes drilled by you with run of the mill metal working tools are usually oversized and will often be ok with run of the mill oversized steel rods.

McMaster-Carr Shipping and Steel

When ordering steel from McMaster remember that anything that fits in there standard 12″ x 18″ x 6″ box is the same price for shipping. The weight does not matter much. So, if you order a bunch of nuts, bolts, etc for your project to go with your steel and the steel is only 18″ in length or less then you don’t pay a lot extra extra for shipping.

If you order anything over 18″ in length then it will come in a 3 foot or 6 foot by 3″ diameter cardboard shipping tube. The shipping tube will add $12 to $18 to the cost of shipping on top of the cost for anything else you order that comes in a box.

See my “McMaster-Carr” blog entry for more info ordering from McMaster.