Loco and Tender Leaf Springing 5in Gauge

[ron61630]

Is there a book or website that would be ideal for first timers...Sort of 'Leaf Springs for Dummies'


Should i go all steal   ot a steel /tufnol mix

If all steel  should some or all of the springs be 'slotted'

If steel/Tufnol what ratios should i be looking at

The steel was purchased from POlly ME  so not sure if already tempered

If Not best method

Best way to treat Tufnol

Has any who has built a B1 or similar done this can give advice

Thanks in advance and a Merry Xmas to all

[chris vine]

Hi Ron,

I don't know, but expect:
the spring steel from Polly will probably already be tempered. If it bends and stays bent then it isn't!

If you can slot the leaves internally so it isn't visible, that will make a more realistic looking spring.

If you can avoid softening them, it saves having the tricky task of re-tempering and risking getting it wrong.
You can drill spring steel with a carbide drill, or you can punch holes. No need to soften for that.
You can also bend spring steel by over bending so that it springs back to the shape you want. Even better is if you then, by hand, unspring it even further. IE you have to overbend it quite a bit and then it will spring back and then you push it a bit more by hand. That will give you a stable spring. Again, so much easier than softening and re-tempering.

Chris.

[uuu]

There's a book by Tubal Cain (who's well regarded) on the subject: www.specialinterestmodelbooks.co.uk/product/spring-design-and-manufacture/

But - I haven't got it, I just know it exists, so I don't know how many of your questions it answers - but it might equip you to work your ideas out. Perhaps someone who has the book can comment.

Wilf

[firebird]

Hi Ron

I don't know if this will help but here goes

On Conway the plans specified leaf springs. The guys down at our club recommended I convert to under slung coil springs which are much easier to set up so that's what I did.

Here's a few clips from the magazine article that was published







Cheers

Rich

[thumpersdad]

As it happens, I have just bought a copy of Tubal Cain's book.

I think it is well worth having: it does cover leaf springs including mixtures of steel and tufnol leaves and springs having leaves milled out to reduce their thickness.  There are formulae for calculating the stiffness of the spring packs, though some of the explanations of the origin of these formulae are a little clunky.

Eric

[ron61630]

Rich, Wilf and Chris

Three replies and all covered. I have enough material to cover everything, even accounting for the amount i scrap before i get it correct!!

One question for Chris, when you mention about softening the steel, what do i need to avoid doing, so i do not

Hope that makes sense lol

One thing i cannot get my head around is that the loco takes 7/16 width 12 springs, whereas the tender is taking 16 springs of 3/8. To my addled way of thinking is more weight on the loco therefore more leaves.

[chris vine]

Hi Chris,

I didn't soften any of the leaves for the springs on Bongo.

I bent them using a press (drill machine) and some formers made out of wood, with some strips of metal to make them a bit more robust.
You could put them through a set of rolls to do the same thing.

Either way, you have to roll them tighter than needed and they spring back. Better is if you spring them back a bit more so that when you let them go they take to the curve you want.
If you don't do this last bit, they will uncurve a little on first loading.

For drilling any holes, or milling slots, you can just use carbide drills or mills. For simple holes, I am lucky to have a little bench punch which makes light work of this. Mind you, the little punchings ricochet around the workshop a bit!!

Having discovered this, I would never soften spring steel to make a spring. If you do, then you have to harden and temper it again. Unless you are clever, they will either be soft and sag, or too hard and snap.
When we harden and temper tools, it is usually only the tip which has to be correct. With a spring, it all has to be correct.

Chris.

[ron61630]

Eric

Thanks for the tip off

I have put an order in for it

Merry Xmas to all

Ron

[weary]

Don't know if you have spotted this posting by Steamtrainfiend on 24th December 2022 at 01:22AM (scroll down) on page 39 in the thread 'Don Young's Black 5' which may be of interest & worth following-up?

+, although I realise that you have purchased spring steel strip don't forget that you could make your springs either fully or partially using phosphor-bronze strip which would be 'softer'.

Phil

[oldnorton]

I will offer a few words of caution. One can make a 'spring' that seems to support a weight, but after some time period and a few up and down movements it may well move to a shape that makes its life easier, i.e. collapse.

I believe that EN42 spring steel strip is usually supplied in a semi-annealed state. That is how my raw material feels. Yes, it may feel a bit springy but if you can roll it to a curvature, or shape it by hand, then it will just as easily return to its previous shape. I have rolled EN42 semi-annealed to make leaves and then hardened them, after which they have to be tempered to the correct blue colour or they will crack. But, it is easier to fully anneal the EN42 supplied before cutting, drilling or shaping. Once you have hardened and tempered them it is almost impossible to remove the set curvature, well, you have to go to extreme deflections.

Tufnol can be thought of as a 'padding' between hardened steel leaves. Without the steel springs it will quickly collapse. I have my doubts about whether phosphor bronze will behave as a spring over an extended time. But, again, as a 'padding between steel leaves it might do a job. Tufnol needs setting to a curvature only because its leaves will not lie properly in profile under the steel leaf (leaves), but it is doing very little 'springing'.

Norm

[chris vine]

Hi Norm,
Not sure what my spring steel is but it took a shape and has retained it despite me sitting on tender.
Part of the knack may be my over loading each leaf to bring it to shape after I put in the initial shape.
Chris

[melaser]

Get the book. However, waste of time making anything until the loco is all but complete. You need a weight to calculate the spring rating, and it's far better done by actually weighing the loco, balancing it, and then calculating the springs required. Annealed CS70 is the material you want to buy, machines just like ordinary mild steel, and then is easily hardened and tempered.

Don't be tempted to coil spring it, they are the work of the devil.

[oldnorton]

Dec 30, 2022 9:25:59 GMT melaser said:

Get the book. However, waste of time making anything until the loco is all but complete. You need a weight to calculate the spring rating, and it's far better done by actually weighing the loco, balancing it, and then calculating the springs required. Annealed CS70 is the material you want to buy, machines just like ordinary mild steel, and then is easily hardened and tempered.

Don't be tempted to coil spring it, they are the work of the devil.

Yes, you need a weight, you need to calculate the spring rating desired AND I would add you need measure the achieved rating of each spring.

Personally, I would hate to wait until the loco was nearly finished until it had its springs   Best to estimate the weight, or weigh all the bits before machining them and do a sum. If you are 10% out on a total weight estimate it will not matter a jot. More tricky to even guess at a front or rear bias.

[melaser]

Dec 30, 2022 13:16:06 GMT oldnorton said:

Dec 30, 2022 9:25:59 GMT melaser said:

Get the book. However, waste of time making anything until the loco is all but complete. You need a weight to calculate the spring rating, and it's far better done by actually weighing the loco, balancing it, and then calculating the springs required. Annealed CS70 is the material you want to buy, machines just like ordinary mild steel, and then is easily hardened and tempered.

Don't be tempted to coil spring it, they are the work of the devil.

Yes, you need a weight, you need to calculate the spring rating desired AND I would add you need measure the achieved rating of each spring.

Personally, I would hate to wait until the loco was nearly finished until it had its springs   Best to estimate the weight, or weigh all the bits before machining them and do a sum. If you are 10% out on a total weight estimate it will not matter a jot. More tricky to even guess at a front or rear bias.

Why?  Makes no difference whether you make the springs early or later, makes no difference whether you make the boiler earlier or later.  I've got the boiler and most of the cab built for my current engine, but the chassis isn't even running on air yet.  There's ALWAYS goingto be something waiting for doing, doesn't matter what it is