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DS1169 part 2 - Bonnet forming.

halfwit

Entry posted by halfwit

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Forming the bonnet

 

The first thing I did was to anneal the brass bonnet by heating it until it turned to a straw colour over a gas flame (cooker). I can never remember whether you're supposed to allow the brass to cool naturally or quench it in water, I just go with the former option. Works for me... Then I soldered one edge of the front panel to one side of the bonnet;

 

blogentry-6749-0-75215100-1322741141_thumb.jpg

 

Then I rolled the bonnet around the first corner, using a 3.5mm drill as a former;

 

blogentry-6749-0-84819600-1322741173_thumb.jpg

 

Gently rolling the bonnet top and soldering it in place;

 

blogentry-6749-0-80508700-1322741184_thumb.jpg

 

And carry on until finished;

 

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Remove the excess metal from the bottom (the bonnet is etched too wide) and solder in place;

 

blogentry-6749-0-43806700-1322741209_thumb.jpg

 

Well, thats how I do it. All the rolling was done on the workbench using my fingers and a pair of pliers. Beware of the half-etched bonnet side detailing, the etched lines try to act as fold lines. Also beware that the annealing will make the brass quite soft and therefore requiring care when handling to avoid buckling.

 

There is probably a far better way of doing this. It would help if the inside of the bonnet has some half-etched lines to help with the corner bends.

 

Anyone building etchy stuff should have a look at Iain Rice's 'Etched Loco Construction' (Wild Swan), probably still the best resource on the subject although in need of updating.

 

This blog in general...

 

Just out of curiousity, do people find this blog easy to navigate, or should I try and re-organise it? (I'd rather not but if it makes finding stuff easier I'll consider it).

Any other thoughts on this blog, good or bad, are welcome as well.

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halfwit

Brilliant - many thanks for this - now to mangle some brass! GRW184

 

No problem, I hope you find it usefull. Perhaps someone else will come along and tell us how to do it properly?

 

Paul.

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boogaloo
No problem, I hope you find it usefull. Perhaps someone else will come along and tell us how to do it properly? Paul.

 

Any heating above a low red heat will anneal brass. The faster you cool it down from hot (ie. quench with eg. water), the more completely it anneals.

 

Other types of metal/alloy (eg. steels) will harden on quenching but not brass.

 

The one exception (as there's always at least one) its Muntz metal(60Cu/40Zn) but this is rarely used in modelmaking.

 

HTH

 

Boogy

(former Heat Treatment technician University of Manchester)

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Jan

Cue Barry Manilow...

 

"Annealing; nothing more than..annealing

trying to forget my ''''annealings of brass.."

 

There is probably a far better way of doing this. It would help if the inside of the bonnet has some half-etched lines to help with the corner bends.

 

I think that's how the Impetus Ruston was done... mine's been soldered up for so long, I've forgotten... Is there no rear bracing/former in the kit? You've pulled this off with nowt but a three and a half mill drill? Blimey. Yet another bonzer job, halfwit.

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halfwit

Thanks for the comments.

 

." I think that's how the Impetus Ruston was done... mine's been soldered up for so long, I've forgotten... Is there no rear bracing/former in the kit?

 

I've just had a peek at my unbuilt Impetus kit (hello collectors!) and it has indeed got half etched lines inside the bonnet. I'm unsure whether to build the thing or sell it... the Impetus kit does have several faults, I do wonder if the designer actually measured a 48DS or just scaled a photo...

 

The A1 kit doesn't have a rear bonnet former, I did think about knocking one up but then it would be so thin and weak, from having to clear the motor, that I didn't think it worth the effort.

 

Boogy - thanks for the info. My method isn't far off then!

 

Paul.

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