Leaf Springs

[Deleted]

Hi Folks,
Anyone out there got any experience with functioning leaf springs?
I'm planning to use them on my USRA 0-8-0 switcher in 3 1/2" gauge with full equalisation, my current thought is to use a top leaf of 0.8mm X 8mm spring steel with the remainder in nickel silver or steel as required. I estimate individual axle loading will be 9kg.
I've used leaf springs in Gauge 1, but not clearly visible as these will be so they need to look pretty close to scale.
Here is where I am at the moment:

[SteveW]

Usra,

NICE!

The only thing I've pick up about model leaf springs is if the look right they won't work right. It's all about not being able to scale real life. Not helpful I know, sorry.

[alanstepney]

Very nice!

About the best advice and data on leaf springs has been by Tubal Cain, in ME (dont have the reference to hand) or in the Model Engineers Handbook. (A book that I believe should be in every model engineers collection.)

Having said that, my experience is that no matter how you calculate it, trial and error, mainly the latter in my case, seems to be the only way.

[Jo]

Tubal Cain's articale is volume 158 (early 1987) pages 205, 354, 466, 588, 698. The same series of articales were put together into the workshop practise book 19 "Spring Design and Manufacture".

Whilst we are on the subject of leaf springs can any one suggest how to stop them rusting? I was thinking of blueing my clayton springs before assy and then keeping them happy under a layer of duck oil. I have seen others having painted them but I would have thought the movement would damage the paint. Is it worth greasing between the leaves?

Jo

[greasemonkey]

Hi Jo
IIRC it is the friction between the leaves that acts like a shock absorber. I would assemble dry and then give a protective coat of something thin then.

Andy

[Laurie_B]

Working model leaf springs can be a bit tricky to make work properly as already mentioned.
I believe that steel leaf springs need to be heat treated properly too.There is one supplier who offers a heat treatment service,I think it is Folkestone Engineering Supplies.

At the last Midlands Exhibition that was held at Donington,I was very impressed by some 7-1/4" gauge locos built by Dave Aitken of Radcliffe on Trent.I'm sure that he had used phosphor bronze strips in his leaf spring assemblies.Mr.A is currently describing a 7-1/4" GWR 2251 class loco and tender in E.I.M.It will be interesting to see what he specifies for the springs.

[ron]

Hi Jo
I use Waxoil on full size leaf springs, don't see why it wouldn't work on model ones.
Ron

[Jo]

Hi Andy,

Having been woken up to my copy of Tubal Cain book on springs I thought I'd see what he had to say: He recommends that model leaf springs should be assembled with a lubricant and suggests the use of a graphite running-in compound such as was used on pre 1930's vintage car springs let down with a thin oil. I assume that graphite grease with any suitable thin oil would work.

Jo

[Noddy]

Andy,
Going from memory, I think Tubal Cain suggested plastic dummy leafs to give the scale appearance, if you are using these, then they should be self lubricating in contact with the steel (as long as some muppet hasn't used something like silica as filler in the plastic).

I'm inclined to agree that friction in multi leaf springs produces useful damping, however if you do go for lubrication, articulated wagons use a very tenacious graphite grease on the "fifth wheel", it sticks like the proverbial does to a blanket!

Ron's Waxoyl is much more user friendly.
hope it helps
K

[chris vine]

Hi Usra,

One neat method of making scale leaf springs is to mill slots in the centre of the inner leaves. That way there is much less material but the slot is invisible. I expect a bit of experimenting will be needed.

I would not even think of softening the spring material, work with it as it is. I think it must be difficult to heat treat reliably. To work it, you can cut it with a hack saw if you go slow, you can mill it with little solid carbide cutters and to put holes in you could either punch it like I do or use a carbide drill. Not too expensive from J and L.

I got my spring material from Reeves, but I am sure others can help.

I painted mine with a thin coat of semigloss black paint. The preparation was sandblast followed by an etch primer. I have not worried about lubrication at all and they work fine so far.....!

If you like I will try to dig out a picture and post it here??

Chris.

[Deleted]

Thanks for your suggestions gents.
Damping was far from my mind as I don't think it is worth considering in 3/4" scale, especially with such small travel. I've tried Martin Evans suggestion of Tufnol leaves before, but can't say it was very successful.
Thanks for the tip on slotting leaves Chris, would appreciate a photo.
I used to drill holes in my G1 springs with dental burrs, obtained 2nd hand from my dentist. The advent of AIDS put an end to that source!

[gilesengineer]

I have no experience at all with thesen(othere than full size, but I know this man does....
- Doug Hewson (models) 73 Victoria Road., Barnetby-le-Wold, North Lincolnshire, DN38 6HY 01652 688408

[Shawki Shlemon]

Hi
First I would like to compliment you on your frame /cylinder finish. On springs ,all leaf springs looks too few ,add Teflon or other materials looks wrong,using dummy and coil spring looks better but is wrong .I have used all of the above, it is a matter of choice and the location of the springs .

[Peter W.]

Usra, there's a lot more information elsewhere in "ME Clearing".
If you use the search facility, last 800 days, threads only,
you should find another 6 threads on the subject of leaf springs.

[chris vine]

Hi Usra,

Here is a picture of a painted leaf spring. The paint was Trimite semigloss black. The paint has not chipped in service. This may be helped by the fact that the edges of the leaves are a bit rounded which means that the joins are a bit hidden.



Chris.

[Deleted]

Mmmmh they look really nice Chris! Beautiful work, you must have spent some time cleaning up those wheel castings.

[chris vine]

Hi Usra,

Yes I spent quite a lot of time with a round file. I started by using an air powered die grinder with either small stones or carbide burrs but the trouble is that it can bounce along the side of a spoke and leave a wobbly surface. It is not like a milling machine where everything is guided accurately.

In the end I used round files of the sort that are made for sharpening chain saws, they are conveniently parallel but don't last too long.

Chris.

[Nigel Bennett]

I used the slotted leaf dodge in my "Edward Thomas" on the leading axle only - I left the rear ones solid as it has Hackworth gear and I didn't want it too mushy. Works fine!

[Deleted]

Thanks for you advice folks, I'm going to get myself a bit of spring steel and do some experimenting.
Here's some I made earlier in Gauge 1, as you can see I cheated a bit and used very few leaves. But then as the whole thing is so small no one really notices, unless they have good eyesight!
On my switcher the springs are above the frame, and with such small wheels, in full view so will have to look prototypical.

[gugger]

For my 3 1/2" B1 Springbok I made the spring leafes from a spring type bronce.

[http://i89.photobucket.com/albums/k206/Gugger_2006/B1/IMG_0009.jpg]

[http://i89.photobucket.com/albums/k206/Gugger_2006/B1/IMG_0011.jpg]

Walter