Stuart S50 - Replacing mild steel shafts with stainless steel shafts.

[Lloyd-ss]

Thanks for this. I do tend to search my scrap box first, but the problem is I dont know what most of the material is! When I buy new material I'll look it up on Matweb and label the remnants for future use. I have recently been given some En1a, which is apparently a mild steel with a lead component. It machines very nicely, so will be a material to use for future projects.

After refurbishing the two Stuart's I have a set of castings for a Stuart Progress to machine. I might need your advice with that


I would like to say thank you to everyone that has given me advice, I really do appreciate it.

Sarah

Hi Sarah,
I looked up the cross reference to EN1a and see that in the USA it is known by the SAE spec of 12L14. That is a very popular leaded mild steel of medium strength that machines very nicely, "a leaded free machining steel."
I have used lots of it and have pieces of it in my metals rack with 12L14 written all over it with a Sharpie, LOL. I especially like it for larger parts where a lot of material needs to be removed. I think you will enjoy using it.
Lloyd

EDIT by Lloyd
I see that JasonB says it does not contain lead but is a free machining steel. I guess the cross to 12L14 isn't totally accurate.

Here is the chart I found it on. I guess it is "similar to," and not "equivalent."

 

[Jasonb]

I'd say your chart is wrong. The heading does not correspond to the items in the list.

1214 or 1213 is the equivelent of EN1A and 12L14 is the equivelent of EN1APb where the L and the Pb signify the lead content

https://www.steelexpress.co.uk/engineeringsteel/EN1APb.html

https://www.steelexpress.co.uk/engineeringsteel/EN1A.html

 

[Sarah]

I'd say your chart is wrong. The heading does not correspond to the items in the list.

1214 or 1213 is the equivelent of EN1A and 12L14 is the equivelent of EN1APb where the L and the Pb signify the lead content

https://www.steelexpress.co.uk/engineeringsteel/EN1APb.html

https://www.steelexpress.co.uk/engineeringsteel/EN1A.html

Thank you Jason and Lloyd

As they say "Every day is a school day"

I'll get a sample of the leaded En1a and see how it machines.

 

[Sarah]

Cast iron is going to be a much better partner than mild steel, but it isn't immune. This is for example why internal combustion engines normally use bronze valve guides if they have stainless valves, whereas cast iron guides are extremely common in engines that have regular steel valves.

It depends a lot on the load and lubrication conditions, with very lightly loaded bearings you can get away with a lot of things assuming lubrication conditions are good. For example, I would expect a piston rod to be ok, it only really slides against the gland on the bottom of the cylinder anyway. On the other hand I wouldn't dare to use austenitic stainless for a crankshaft running in cast iron bearings, that's a bad combination. You might get away with it on a model engine simply because the operating stresses are so low (the engine isn't driving anything, and running at very slow speed) but my inner engineer would mad with me for violating good practice. I'd use carbon steel for this and keep everything well oiled to stop rust.

Austenitic stainless will run acceptably against bronze under moderate loads, so another option would be to install bronze bushings in any part that runs against your more heavily loaded stainless parts.

Thank you Nerd for your comments I have a few models to build and I'll continue to use mild steel for the loaded shafts.

Sarah

 

[shorrog]

Try these people which is where I get mine they go down to 1/4" in imperial or 6mm in metriv. Page 88

https://www.m-machine-metals.co.uk/downloads/Metals catalogue.pdf

Just had a look at their catalogue, best selection I have ever seen and their prices seem good.

 

[Sarah]

With the refurbishment of the S50 the main shaft, which the flywheel was on, was replaced with silver steel to take up the slack the original shaft had. The piston rod had a little play and was replaced with a new section of mild steel.

Pictures below are before and after the refurbishment.