The Home Machinist!

To close the loop on this: I successfully machined all 4 crank pins out of 1144 “ultra-strength” steel. Advertised at Rockwell 30c. The material was pretty easy to machine. I was able to hold the tight tolerances in the drawing, with my micro mark 7x16 lathe. Although I hit most of the final dimensi...

for that it is worth, I use 1144 (stress proof) for all my axles and pins. I do not harden pins. so far this has not been any issues with wear. but i also run propane fired locomotives so i do not have any issues with coal dust etc. I’m so far away from the boiler, it’s not even funny. That said, I...

Ok. So here is where I think I landed:

1144 for the crank pins.
I found some annealed 303 for the side rods. Yeah, it was speedy, but for a model of this size, and the slow speed at which I work, the $80 will be survivable.

Fatigue proof sounds promising. I’ve got a lot to read up on. As an aside. What do people like to work with when it comes to flat steel stock such as the side rods themselves? I picked up cold rolled 1018, as Kozo provided just “steel” as the specification. I now wonder how well that will machine, a...

I have some stressproof on hand. And have machined it with success. That would be the easiest approach for me (by far).

I just tried this. Much failure ensued. First shot in the real part: I way over heated it. I don’t think I appreciated how fast it would pass Cherry Red color. Part was pitted and soft afterwards. Quickly made a part approx the same size and tried again. No pitting. Part shrunk approx 0.0008”. Unfor...

Enlightening discussion! I made a test pin from hot rolled mild steel and case hardened (kasenit) the rod bushing end and left the end to be pressed into the wheel 'soft', just to see how much the pin diameters changed after heat treating. After buffing the treated pin with emery cloth, both the ca...

I assume you are running bronze bushings on it and not needle bearings. Correct - If I recall correctly all of the rods run on bronze bearings. Earlier today I placed an order for Cherry Red and 12L14. I *guess* I'll try the 4140 HT route if that fails. If nothing else it will be an interesting lea...

Hmm watching YouTube videos case hardening “in a can” looks to be the most approachable option. McMaster Carr has Cherry Red. I needed to order something else from them. I have 1144 stressproof on hand. I presume that is too high carbon content? Can you case harden leaded steel (12l12), or is it bes...

Thanks for input so far. The idea of polishing post hardening is one I had not considered. 4140 half hard is also interesting. I only found machinability data for fully annealed. I’m stuck with my sieg 7x16 lathe, so need to work within its capabilities. I’ll consider this path too. I’m diligent and...

Hi. I’m a newbie building a Kozo A3 per the book (3/4” scale, 3 1/2” gauge) Kozo calls for hardened crank pins (with tolerances measured in 0.0001!). My first attempt with machining A2 to this tolerance was an abject failure. Which makes me wonder ... how common is it to harden this part “in real li...

Question: What material were you drilling? If it was a brass alloy, you should dull the two cutting edges on the drill to prevent that grabbing, especially at the bottom of the hole! Kozo H. describes how to do the drill modification in his books. It is “1/2 hard C360 brass” from online metals. I’v...