Hunslet 5″ Loco

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Hunslet 5″ Loco

This topic has 7 replies, 6 voices, and was last updated 4 March 2010 at 19:49 by calder percival 1.

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28 July 2009 at 18:22 #42537
Brian Brown 1
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@brianbrown1
Hi all,

I’m currently approaching completion of my 1st locomotive, a 5″ Hunslet to the Don Young design, but try as I may, I have not been able to form the brass cowling that wraps around the rear of the firebox backplate / outer wrapper joint. The cowl is a 2″ wide brass strip in half round section and is curved through a 17 1/2 ” diameter for 180 degrees, with the remaining legs on either side continuing half round but straight in order to cover the vertical joint.

I hope that makesense!

I’ve tried clamping sheet brass between 2 formers and heating/beating, but I still end up with creases. I’ve also tried forming a half round srtaight section and coaxing it around the radius, again to no avail. Pressing seems to be the answer, but I don’t have the means or wherewithall to machine a set of dies.

I realise that the cowl is purely cosmetic, but as it adds immeasurably to the appearance, I would really appreciate some advice as to how approach this task before I ruin any more sheets of brass!

Many thanks,

Brian Brown
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28 July 2009 at 18:22 #4724
Brian Brown 1
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@brianbrown1
28 July 2009 at 19:18 #42538
David Clark 13
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@davidclark13
Hi There

Could you turn the top bit, cut it in half, make the two uprights and

silver solder together?

regards david
29 July 2009 at 11:50 #42544
Ian Abbott
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@ianabbott31222
Is this a solid half round, or a shaped piece of metal like half a tube?

If it’s the latter, how about starting with a 2″ tube and having it bent at an auto exhaust shop, then splitting it along the centre line.

A casting would work, but rather expensive.

Regards

Ian
26 February 2010 at 16:50 #49214
Speedy Builder5
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@speedybuilder5
Could you use copper instead – its a bit more malleable.
26 February 2010 at 18:49 #49221
mgj
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@mgj
Ian I suspect that may be a very good answer . Sounds like 1/2 a tube over some kind of flange or joint..

Otherwise its a former, a set of proper tin bashers hammers, and start shrinking and expanding. And keep annealing! Unless you have access to a proper (English) forming wheel.

To do it round a former is quite simple (in concept!!!!) You need a contracting hammer. You anneal and start deforming the metal (with a soft face mallet is best). It will start to wrinkle – of course. Out comes the contracting hammer. Shrink the wrinkle, and take it out. And so you go on, annealing frequently as you go. You may find as the metal thickens in places you need to file some off. Finally draw file and polish up.

Simples – until you try it. But that’s how to panel beat it.

(A blunt file makes a reasonable contracting hammer, if you want to experiment on some scrap. Not as good as the real thing, but adequate. Bit slow, but it will take the wrinkles out.

Edited By meyrick griffith-jones on 26/02/2010 18:49:33
4 March 2010 at 19:48 #49401
calder percival 1
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@calderpercival1
the secret is to take it all together steady and re heat don’t go bashing in one area. heat, beat ,trim, heat it will work just do it slowly
4 March 2010 at 19:49 #49402
calder percival 1
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@calderpercival1
the secret is to take it all together steady and re heat don’t go bashing in one area. heat, beat ,trim, heat it will work just do it slowly
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