Author Topic: bending very large circles?  (Read 4155 times)

Offline RipSlider

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bending very large circles?
« on: June 21, 2009, 04:12:10 AM »
Hello all.

Sorry for two posts in a day.

I need to bend some brass round section ( solid, 6mm dia. ) into a circle - a neat circle, rather than the cack-handed, lumpen attempts I have produced so far.

The circle needs to be 15.5" in diameter - 7.25inches in radius.

Is there I way I can do this without rolls? And if I do need to go down the rolls route, will an average "benchtop" set that you see in the catalouges be enough, or will I need a big set?

Many thanks

Steve

Offline sbwhart

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Re: bending very large circles?
« Reply #1 on: June 21, 2009, 04:58:46 AM »
Steve

I can give you one tip that may help, you need to anneal the brass, just bring it up to red heat and either quench or let it cool, you may have to do this two or three times bending the brass in stages between anneals.

Hope this helps

Stew


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Offline John Hill

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Re: bending very large circles?
« Reply #2 on: June 21, 2009, 05:07:45 AM »
One useful tip for bending a circle is to start with material considerably longer than you need and to bend it around a former smaller than your required finished size.  Once it is bent you then precisely measure the length  required and cut equal lengths from each end.  Not really a precision method but about the best you can do without something like rollers.
« Last Edit: June 21, 2009, 05:09:18 AM by John Hill »
From the den of The Artful Bodger

bogstandard

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Re: bending very large circles?
« Reply #3 on: June 21, 2009, 06:21:48 AM »
Steve,

I doubt very much whether you will be able to get it exactly perfect by manual heating and bending, purely because when annealing by hand, it will never be exactly the same softness all along the rod and that will cause flatter areas than others. The only way to achieve consistent annealing would be to use a kiln where the whole length would be temperature controlled.

What you require is someone who has a rolling machine with ring grooves, then you wouldn't even have to soften the metal, it will curve it whilst still in a hard state.

The 12" rolls on my 3 in 1 has the largest ring roller at 6mm, so going by that, maybe a normal roll set of 12" would be OK. You would have to contact the supplier to see what the max diameter of material it will form into a ring. The overall diameter of the job shouldn't come into the equation, just the diameter of the bar.

I don't know where you live in the UK, but maybe another member within easy striking distance has a set of rolls you could use.

I think Ralph has a set in north Wales, mine are in south Cheshire and I am sure if there is anyone else nearby to yourself, they would be only too willing to help you out.

If you only wanted a couple or three parts making, it might be cheaper to take up the offer of help rather than fork out a fair amount of cash for the machine. But if you could use one again, only then consider buying one. They are a thing not used very often, but when they are needed, having one is indispensable.

http://www.rdgtools.co.uk/acatalog/FOLDER_S___BENDER_S.html


Bogs


Offline Brass_Machine

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Re: bending very large circles?
« Reply #4 on: June 21, 2009, 09:41:42 AM »
Hello all.

Sorry for two posts in a day.

....

Don't worry about 2 posts in a day. You can post more than that if you want!

Eric
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We're all mad here. I'm mad. You're mad.