View Full Version : Leaded steel

11-08-2006, 09:47 AM
The new engine project in HSM calls for leaded steel for the cylinders. Don't see this material listed on any supplier web sites.

Is there another name for this steel???

The author also states not to substitute. Suggestions please.

11-08-2006, 09:51 AM
Try 12L14 Gary

Wonderful stuff to machine.

11-08-2006, 09:56 AM
leaded steel is just free machining steel, 12L14 iirc. free machining steel is generally created by one of two means, adding sulphur or adding lead.

Its nice to work with, but not sure of any mechanical property that would cause the author not want a substitute. what type of cylinder, engine etc? generally steel is considered a poor bearing surface, if its the cylinder of an engine (vs a pump or hydraulic or whatever) I wonder if cast iron wouldn't be a better choice......then again the author must of had his reasons. tell us more about it and maybe can decipher those reasons

11-08-2006, 10:16 AM
The author cautions against substituting materials with good reason, and gives an example of using the wrong material for a bearing. While he recommends leaded steel for it's free machining properties, he does not insist it is the only material to be used for the cylinders.

Cast iron might prove to be a better choice in this application, but leaded steel will work as well in most cases, as engines of this type are not run hard or for extended periods.

Forrest Addy
11-08-2006, 10:25 AM
The cylinder is finned I'm sure and the fins are machined in with repeated plunges with a parting tool. Free machining steel is sure a good way to go for cutting these features if the only requirement you were concerned with was machining them. However this stuff does not wear well and it rusts freely.

I suggest a better choice would be an alloy or tool steel. While it'a certainly stronger and tougher and machines a bit less readily it poses no machining problems a little additional time and sharp tools won't solve. If your piston has rings, I would suggest an alloy cast iron.

Free machining steel certainly has its place and that is in a high volume production setting where tool life and low rejection rate from machiniing defects are of paramount concern. It's not a good choice in the beginner's shop because it's like training wheels on a bicycle. The user is reluctant to take them off and gain the benefits of exploring the wide world accessible without them.

Trust me: there are far more difficult materials to machine than those that are non-leaded - a cobalt chromium welded valve seat 10" deep in a 2 IPS globe valve body for example or manganese steel rail track components.

11-08-2006, 12:12 PM
The cylinder is not finned, it is a watercooled engine. The cylinder is built up, with the water jacket silver soldered in place. A cast iron cylinder could be substituted with no problem. There is not enough wall thickness to accomodate a liner, which is another alternative.

Since construction of the cylinders will require the tapping of 32 4-40 holes, the recommendation of leaded steel is not unfounded.

The engine is built mainly of aluminum and leaded steel, most likely for ease of machining. Since most of these types of projects are for purposes of display and the enjoyment of building them, there is no shame in making the build as simple as possible. There is little to be gained by the use of exotic or difficult to machine materials.

Most HSM's are on a learning curve. The first things to learn are the basics of machining. Those include working from a drawing and making a part to dimension. That presents enough challenges, and adding difficult to machine alloys into the mix will only result in frustration and discouragement.

11-08-2006, 01:01 PM
I have to agree with Jim but I want to add one point for the folks unfamiliar
with this material.

12L14 will rust at the slightest provocation. Despite being kept in closed
display cases in Southern California's arid climate, parts made from this
material have developed a slight film of rust. Easily removed with steel wool,
Scotchbrite, or a polishing buff but still an annoyance.

When your model is finished, give it an occasional spritz with an aerosol can
of pressurized oil such as Starrett M2.

11-08-2006, 01:03 PM
What I've read about 12L14 and other leaded steels, as used for wheels in Live steam hobby, it has the same wear patterns as if the wheels were made from cast iron. And yes, thats how I can spot leaded steel in my scrap bin, it's the piece covered in rust.

11-08-2006, 01:45 PM
Not quite as easy to machine as 12L14 but 41L40 offers much more strength and wear resistance. It might help with the corrosion problem too.

11-08-2006, 02:01 PM
I knew cast iron could be used as the cylinder, just wanted to see what you all had to say about this leaded steel.

Thanks for your response.

11-08-2006, 06:55 PM
I just received the magazine and this engine is a definite item on my to-do list. At the moment however, I not skilled enough to tackle a project of this complexity. (I first need to complete the diesel engine I started!!!)

I figured that another reason for not using cast iron would be the problem of silver soldering it to the water jacket - I thought CI would be prone to distortion. Am I all wet here? Wouldn't 1144 (stressproof) be a better choice?

One way I have found re preventing rust on 12L14 is to use successively finer grades of wet and dry paper with a liberal dose of oil to polish the part. None of the items finished that way have rusted, yet the cut ends of the raw material always rust.



11-08-2006, 10:10 PM
I think 1144(stress proof) is great stuff. It machines very nice also, not quite as easy as the buttery 12l14 though. I would imagine you could use it where ever 12l14 was speced if you wanted to use a higher quality material.

11-08-2006, 10:29 PM
I have machined brass, silicon bronze, tool steels, aluminum, plastics and even exotic hardwoods. As far as I know I have never machined leaded steel. Am I missing something? It isn't available here except on special order.

J. R. Williams
11-08-2006, 11:34 PM
The Leaded Steel 12L14 machines so nice you will want to toss all your CRS stock. Do not try to electric weld the stuff as the bead will be full of gas bubble holes.


11-08-2006, 11:52 PM
1144 stressproof is a good sub,so is the 41L40 niether flash rusts as bad as 12L14.