Finishing leaf springs

[BaldricParticipant @baldric]

I am making a 3″ Foden and have just made the leave springs for the rear using BDMS as specified in the drawings. Before final riveting has anyone got suggestions on how to finish them? The options seem to be

1. Paint after finished

2. Chemical blacking

3. Heat and drop in oil

 

Should a grease be put between the leaves or just left with nothing between them?

 

Thanks

 

Baldric.

[BaldricParticipant @baldric]

What finish to apply to leaf springs

[SpringbokParticipant @springbok]

I would say option3 then use a good molubidium grease inbetween.

but could be shot down for sugesting this

 

Bob

[Phil PParticipant @philp]

Are the leaf springs just dummies that do not need to work ?

 

The reason I ask is that BDMS seems an odd choice of material.

 

Phil

[BaldricParticipant @baldric]

Bob

 

Thanks for that I will try option 3, looking at another thread I will use a heat treatment oven I have access to as my home oven only goes to 250c.

 

Phil

 

The springs are working springs, they are quite hard but there is some spring in them, I guess they need to be harder than scale as they will need to take my weight.

 

Baldric

 

 

[SpringbokParticipant @springbok]

In this scale they will really need to work, I think that it is a slight typo and is BMS

rolling then tempering in oil will give the spring required then grease between leaves then fix the lot together.

 

Bob

[BaldricParticipant @baldric]

The drawing does state BDMS and in the model engineer article the author state something like “use bright drawn mild steel, with no further heat treatment, it has worked for me”

 

Would you recommend tempering then? I guess that will produce a slightly softer spring as any hardness due to working the material will be gone.

 

Baldric

[mgjParticipant @mgj]

Why bother with popping it in the oven. Its bright drawn mild so it isn’t heat treatable. You might remove the stresses from manufacture, but you are not going to alter its mechanical properties by that.

 

Put them together dry, and if they are a bit firm you could try reducing the damping (interleaf friction) with some grease, or possibly some tufnol leaves. Its all to do with the stress you operate at – there is a quite a bit of spring in mild, especially over a short travel.

 

I did that for my Little samson. the drawing called for spring steel – it got plain mild, and they work fine, relatively lightly (stressed) loaded over a short travel.

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