Hi Chaps
I was going to put this as part of my Loco build, but thought it made a nice mini project and bring in the topic of case hardening.
C Spanner
The gland bolts on the steam chest of my Loco build, when assembled won’t be very accessible, they have two cross screwdriver slots with the slide valve rod running through the middle. Adjusting them without damaging the screw will be difficult and replacing them will be a complete strip down job, what’s needed is a bespoke C spanner.
I’ve made the spanner from some ¼” mild steel plate, that I’ve case hardened.
Mild steel has a low carbon content and can’t be harden, but if you soak the material at temperature in a carbon rich environment the surface of the material takes up the carbon allowing the surface to be hardened:- this is case hardening. In the good old days this process was used a lot particularly in thing like shafts where you could have a hard wear resistant surface but with a tough core.
What you need:-
1:- Gas burner.
2:- A hearth.
3:- Case hardening powder, I got mine from
www.chronos.ltd.com in the UK.
4:- Quenching water or oil.
Method:-
1:- Machine the spanner to the finished shape.
2:- Bring it to a nice bright cherry red on the hearth. Tip:- try to do this in natural light to get the true color.
3:- Bury it in the hardening powder and leave it there to cool.
4:- Remove it from the powder, leaving all the crusty powder on it, and bring it to cherry red again and hold it at this temp to burn the powder in a bit more.
5:- Quench in the water.
6:- Clean and polish
Job Done
Quick check with a file and you’ll find it skids over the surface
This is the way I do it some of you Chaps may have better ways but this works fine for me.
One final thing don't set fire to your shop
Have
fun
