Boiler wrapper

[Billy BeanParticipant @billybean67480]

I have to form a firebox wrapper for a boiler barrel which is 2.5 inch diameter.

Wrapper material is copper, 11 inches long by 3.5 inch by 16swg and it will be a true half circle with two legs – ie just like the letter U in section – hopefully that makes sense.

Not made one before so am thinking a set of Warco rolls would be the best road to go down.

Presume rolled area will need to be annealed ?

Advice appreciated.

Thanks

BB

[Billy BeanParticipant @billybean67480]

[FMESParticipant @fmes]

HI BB,

Normally a wrapper of this shape would be formed over a wooden former made to the inside dimensions of the required shape..

I hope that makes sence, using a set of rolls would make it very difficult to end up with the correct dimensions.

So, make a former out of a hard wood if possible, anneal your copper that has first been cut out to the required plan shape, and after annealing, gently hammer the copper round the former.

You will only be able to go a small way round the former before the copper will require annealing again, don't force it, you are likely to end up with it cracking.

Hope this helps,

Regards

Lofty

[JasonBModerator @jasonb]

You should not even need a hammer just bend the wrapper around your former by hand. I would suggest making the strip a bit longer than needed and then trim after bending that way if you don't get the bend central it is not such a problem. Won't need annealing more than the initial time and probably won't even need that.

A bit of ply or MDF to apply the hand pressure will make sure the bend forms where you want it and the legs of teh wrapper stay straight.

[Billy BeanParticipant @billybean67480]

Thanks replies.

Could the boiler barrel be used as the former as the wrapper fits over this at one end ?

Just a thought ?

Thanks

BB

[JasonBModerator @jasonb]

Yes although something a little smaller dia may be better so that the wrapper springs back to the required size. Probably worth making the tubeplate first and slipping that into the barrel to stop it distorting if you get a bit heavy handed!

[Bruno TaylorParticipant @brunotaylor21701]

Hi Billy

Just done the same, did the first bend in the rolls, the second free hand using the end plates as formers. The copper must be kept well annealed then it bends like paper. Judicious taps with a planishing hammer gets the nice tight fit you need.

Keep on bashing.

Regards, Bruno

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