Bending Brass Sheet To A Slightly Curved Shape

[Mikegtr]

How thick can I bend a thin brass sheet without annealing the brass? I want the brass sheet to fill a small gap between metal and wood--a slight curve. The gap is 10mm deep.
I recently bought a small sheet of brass 1mm thick thinking that would do the trick. The sheet will bend --with force-- but the job I want it for is a musical instrument so I want a pliable strip of brass to take the curved shape . No problem the get to the 1mm gap using thinner thickness brass to build up to the 10mm I want. Your advice on what thickness to get so it will bend into shape without annealing?

After a bit of research would half-hard brass bend to automatically take the curve?--without annealing? If so what would be the maximum thickness of the brass plate?

 

[frogesque]

Not quite sure of your problem but 1mm brass is normally OK to bend by hand. You need the Yuri Geller fingers and feel the brass as it just starts to get from the stage where it springs back to the point where it goes plastic and starts to retain the curve after the pressure is released. Takes a bit of practice but it's quite satisfying.

For a large sheet and 3D shaping you need planishing hammers, form tools and maybe a sand filled leather dolly. Brass work-hardens fairly quickly, copper or silver are much more pliable.

 

[bourbon]

what is you aversion to annealing? heat up, quench, bend, polish back the shine

 

[AES]

The other trick you can try is to use (ideally) a soft-ish sandbag, check the grain of the brass so that you're curving it WITH the grain, then "roll over it" with a "rolling pin" (just like Mum/wife/sister rolls out pastry, using the palms of your hands pressing down equally on both ends of the roller, which should be long enough so that it overhangs the sheet at each end). The "sandbag" can be a fairly large pile of newspaper, ideally arranged so that it has a dip in the middle, where you want the curve to start. And the "rolling pin" can be a SMOOTH piece of quite large dia hardwood, or better, a steel rod. Again make sure it's smooth, and the bigger dia the better.

Be prepared that the curved sheet will spring back toward flat, even after 2 or 3 rollovers probably, but as the curve starts to appear and stay more or less in shape, go SLOWLY and GENTLY, checking against whatever the job is, as once you've curved it too far it will be the devil's own job to "un-curve" it. DAMHIKT!

This is a trick I've used quite often (not only with brass but also with sheet copper and aluminium). At 1.00 mm thick, you shouldn't have any problem with generating the curve, even if the brass you use is not half-hard.

But what have you got against annealing the brass in the unlikely event it proves stubborn?

 

[Normancb]

A lot of commonly available brass is CZ121 alloy. It will bend but usually needs annealing. If you ask for CZ108. that is a cold-forming alloy and will bend much easily without annealing

 

[John on the Wirral]

In the early 70s I built a kit car which was basically a square tubular space frame and everthing else was aluminium in one form or another but unlike modern kits they just gave you the materials and you had to work it. They suggested that where sheet ally neded to be curved you should "break" it by pulling it backwards and forwards around a lamp post until the required curvature was obtained and it did work.

 

[AES]

Yeah, it would work, depending on the thickness of the ali, and whether or not it was annealed. BTW John, did you notice by any chance that the piece work hardened after you'd curved it?

Anyway, you described exactly the same principle that I suggested above.

 

[John on the Wirral]

Never needed to consider it as it was bodywork so was held in place but I knew from experience that it would look like a threepenny bit(that dates me) if I didn't break it. What you need is an English wheel which does what a rolling pin does but a lot easier Cheers John on the Wirral

 

[AES]

Yeah, thanks for that John. I think.

I'm sure that many here know what an English Wheel is, possibly even the OP. But bearing in mind the size of those things, not to mention the price, even SH, AND remembering the guy was talking about curving what sounded like quite a small piece of brass - something to do with a guitar I think (?), but certainly NOT car body panel size), don't you think that an English Wheel would be a bit of an elephant to crack a nut inn his case?

Any yeah, thanks, I also know what a threepenny bit is/was. I'll raise you a tanner!

 

[frogesque]

Yeah, thanks for that John. I think.

I'm sure that many here know what an English Wheel is, possibly even the OP. But bearing in mind the size of those things, not to mention the price, even SH, AND remembering the guy was talking about curving what sounded like quite a small piece of brass - something to do with a guitar I think (?), but certainly NOT car body panel size), don't you think that an English Wheel would be a bit of an elephant to crack a nut inn his case?

Any yeah, thanks, I also know what a threepenny bit is/was. I'll raise you a tanner!

Thrupney Joeys were round, and silver!

 

[J-G]

Thrupney Joeys were round, and silver!

That was prior to 1944 - or 1942 if you only allow Local UK issue (rather than Colonial).