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Spring bounce


Pugsley

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An appropriate title in a couple of ways, one, that the first of the production primary springs have taken shape this afternoon, and the coming of Spring has given me a chance to get on with this madcap scheme.

 

So, for starters, a view of the first bogie with one of the equalising beams in place, on the first two springs:

blogentry-6668-0-50558400-1300041940_thumb.jpg

 

To the front left are some more springs in various stages of completion. The long coil of wire behind the individual springs is how it starts. This is 0.61mm soft copper wire wound, under tension, around a 3.3mm drill bit, making sure the coils are lapped up tight to each other. The next stage involves stretching this out until there's roughly 1.5mm between the coils, which is the stage this particular example is at.

 

The next step is to cut the large spring down to make the individual springs, which are 7 coils each. Each end is levelled and the spring recompressed, before the end is filed to make it sit level. These then fit onto the studs on the sideframe and the equalising beam. The next photo shows it in close up, with one of the prototype secondary springs loosely plonked in place to give an idea of what it'll look like:

 

blogentry-6668-0-68747000-1300041947_thumb.jpg

 

And this is what it's supposed to look like:

blogentry-6668-0-27091300-1300041936_thumb.jpg

 

It's close enough for me!

 

The next job, after finishing another 14 springs, is to work out how far out the stirrup needs to be packed out from the front of the hornblock, followed by filing down the equalising beams to fit in the stirrups.

 

It's been a long time coming, but it really does feel that the end is in sight for this project, at last!

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I can't wait to see a video of this running Martin!! I hope you build some less than perfect track for it to run down and evoke those original thoughts you had about overgrown sidings in the Sandbach/Middlewich area...

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Martin, piddly wee bits of valve gear is nothing compared to what you're doing here.

 

Mind and blacken them springs chemically, as I suspect paint may well flex off in use.

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Great stuff as always. One thing that worries me though is whether the copper springs will retain their springiness. Won't they compress over time?

 

Cheers

Dave

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Thanks for the comments everyone.

 

James - I hope there'll be a video of it at some point, there will certainly be a short demonstration track for it to run on at some point, as there's some techniques I want to try before building the layout proper. The layout is some way off though, I have to build a bit more stock first, including designing my own wagon kits!

 

Jamie - That's a good point about the piddly valvegear, but this is a lot less fiddly than that, and building something from new is often easier than modification. Good thinking about painting the springs, I'll have to check out how to chemically blacken copper.

 

Dave - I must confess that worries me too. Unfortunately, the only way I'll find out is by doing it! If they do compress over time, I guess I'll just have to renew them

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This is amazing!

 

I love the springs! Was the intention to make them actually work or are the just cosmetic? To make them work I think you would need something a little stronger than copper, maybe brass or nickel silver or similar. I agree with Daves comment about the longevity of the copper ones.

 

The building of this is brilliant, I cant wait for the next post.

 

M. :)

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Thanks Missy, glad you like it!

 

Yes, the springs are designed to be fully functional, in more or less the same way as the real thing. The only difference is that the platform that the springs mount on isn't pivoted on the model.

 

I have experimented with other wires for the springs, including phosphor bronze, nickel silver and brass, and found that everything apart from copper produced springs that were far too strong. By the time I've got everything riding at the right height I think I'll have had to add a lot of weight in the model as it is, if I used anything stronger, it would have to be really heavy.

 

I've subjected my springs to an extreme weight test (ie I stood on one to see what happened!) and that lost some of its spring, but it was still sufficient for use. I've added another coil now, which will help, I think.

 

More later, as I've done a bit more with the axleboxes. It's really coming together now!

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