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Bending Brass - Advice sought

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9fingers18/01/2015 10:19:19
28 forum posts
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I want to make a quantity of the part shown in the drawing from stock brass angle 10 x10 x1.5 or imperial equivalent.

bookcase end stop.jpg

Where suppliers state the type of brass angle they tend to quote CZ121 which looks to be formulated for best machining quality rather than bending.

I need to start from stock material as I don't have the equipment needed to form the angle from sheet stock which has optimum bending qualities.

My question is how readily can 1.5mm thick CZ121 be formed to a 5mm radius on a scale from "piece of cake why even ask" to " you have got to be joking mate"

Also will heat be needed - desirable - helpful - essential etc

This will affect how I design and build the bending tool.

n.b. The overall length will be about 300mm. The drawing just shows this particular formed feature.

 

TIA

Bob

Edited By 9fingers on 18/01/2015 10:32:50

JasonB18/01/2015 10:23:52
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Assuming the length is to scale I would make it from two strips of a more easily bent grade of brass and solder together to form the angle

9fingers18/01/2015 10:31:15
28 forum posts
3 photos

Hi Jason,

Thanks for the rapid response.

No sadly the length is not to scale - overall about 300mm and I'll need to make about 20 off.

They are part of a guide system for barrister bookcases that I'm making to a custom design.

Bob

Michael Gilligan18/01/2015 10:34:10
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Posted by 9fingers on 18/01/2015 10:19:19:

Where suppliers state the type of brass angle they tend to quote CZ121 which looks to be formulated for best machining quality rather than bending.

I need to start from stock material as I don't have the equipment needed to form the angle from sheet stock which has optimum bending qualities.

.

Bob,

You probably know this already,but CZ121 has poor ductility.

MichaelG.

[quote]

Brasses are divided into two classes. The alpha alloys, with less than 37% Zinc, and the alpha/beta alloys with 37-45% Zinc. Alpha alloys are ductile and can be cold worked. Alpha/beta or duplex alloys have limited cold ductility and are harder and stronger. CZ121 / CW614N is an alpha/beta alloy.

 

Edited By Michael Gilligan on 18/01/2015 10:36:26

9fingers18/01/2015 10:45:08
28 forum posts
3 photos

Thanks Michael, I did not know that but I'm getting the picture.

Looking at your link, CZ121 seems to be workable hot which could be an option - anyone got experience?

I presume the angle must be hot drawn in the first place?

Alternatively Is angle available in consumer quantities in cold forming alloys? Bearing in mind that I also have to do some limited machining on the parts to a visible standard eg clean csk holes.

Bob

julian atkins18/01/2015 10:50:16
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hi bob,

i would heat the end/s to be bent to dull red and then add your jig. this grade of brass melts easily so dont overdo the heating! i have regularly annealed and bent old brass curtain rail to quite small radii

cheers,

julian

9fingers18/01/2015 10:59:07
28 forum posts
3 photos

Hi Julian,

Thanks for your reply.

Are you suggesting the heat to anneal the brass followed by cold(cooler!) forming or forming whilst at dull red temperature?

The latter will mean my jig will need to be quicker fitting than the current back of envelope design supports with several screws to be tightened before bending.

TIA

Bob

Edited By 9fingers on 18/01/2015 10:59:32

Edited By 9fingers on 18/01/2015 11:00:04

Russell Eberhardt18/01/2015 11:54:07
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2574 forum posts
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I would take the practical approach. Try bending a bit round some 10 mm bar cold. If it works, good. If it doesn't work try annealing it first. If that's no good try hot bending. If all else fails silver solder a bit of sheet material onto the end.

Russell.

9fingers18/01/2015 12:09:15
28 forum posts
3 photos

Possibly a good idea. I've just ordered a sample from fleabay.

Cheers

Bob

Circlip18/01/2015 12:48:17
1089 forum posts
Posted by julian atkins on 18/01/2015 10:50:16:

hi bob,

I have regularly annealed and bent old brass curtain rail to quite small radii

cheers,

Julian

Yes but don't forget Julian, "Old Brass curtain rail" was ductile enough to be hand bent to suit - Curtain tracks and definitely wasn't CZ121.

Regards Ian

Neil Wyatt18/01/2015 13:18:53
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17742 forum posts
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There are definitely different grades out there. I have had angle that just won't bend, and other stuff that does.

That said, if you make a custom bending jig to use in a vice or small press, it should be possible to put that bend in OK, with a bit of experimentation,though you may have to anneal it.

<edit>

We are terrible for putting theory ahead of practice on this website. OK this is 1mm not 1.5mm angle, but it's just a cheap extrusion from one of the DIY sheds. Roughly cut a tab with a razor saw, clamped it against a bit of steel bar (about 9mm diameter) in the vice and gently tapped a few times with a nylon faced hammer.

I can't see this task is going to need any special techniques.

Neil

cold worked.jpg

Edited By Neil Wyatt on 18/01/2015 13:37:10

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