cold bending bronze in NC

[Cecil Borel]

I am beginning to work on the bulwark (toe rail) for Janetess. I need to bend 26 pieces of bronze to an 88.5 degree angle. I think the job could be done by cold bending on a hossfeld bender. The bar is 2" wide by 1/4" thick. Attached is a picture of the design. Does anyone know a resource in North Carolina in the triangle vicinity?http://gallery.mac.com/cecilborel/100015/bronze-20bulwark-20drawing/web.jpg

[S B]

Just guessing, but you can probably order a piece of plate, 6', bent to the proper angle and arms. Then saw off identical pieces, easier and more accurate than 26 individual bends..

[Jay Greer]

It depends on what alloy you are dealing with. Phosphor Bronze was once offered in three grades of hardness. Now, there is only one. And it will fracture if bent 90 deg. Everdure is much more forgiving. I would think that your supplier would be able to offer you criteria as to how much cold bend their material will stand.
Jay

[George Ray]

http://www.mcmaster.com/#bronze/=3roa62

Click the link for Bronze and you should get the table of characteristics and list of alloys with information on each.

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Note:
If someone asked if bronze can be cold worked the answer would be just as easy as answering the question, "are people forgiving". => answer => 'It varies!'

[Cecil Borel]

Thanks for your responses. I am using high silicon bronze, C655 from atlas metals. I understand that it has good to excellent bending characteristics.

[kc8pql]

I am using high silicon bronze, C655 from atlas metals. I understand that it has good to excellent bending characteristics.
That's correct. I used 655 for chainplates, gammon iron ect. on Alaya. It cold bends quite nicely. I used a press brake to do the bending.

[Bob Triggs]

My first thought would be to have a good fabricator make up a length in that profile, with the desired bronze alloy etc, like an length of angle iron, and then just cut off segments to length and finish the edges, install bracing etc yourself.

[seo]

The metalworker that I learned the following trick from referred to brass and bronze as being "hot short," which he said meant that it work hardens as it's bent to much, and then has to be annealed before it can be bent more.
It's unlike steel, which can be heated to red hot and then becomes malleable.
The trick is to bent the metal piece (maybe ten degrees: depends on the alloy) to the point where you can feel it start to stiffen up (work harden). Then take an acetylene torch, and turn the oxygen off, and coat the part with acetylene soot. Then turn the oxygen on, and with a normal heating flame heat the work piece until the soot burns off. That's hot enough. Then stick the piece into a bucket of ashes (NOT WATER!) Let it cool, and then bend it some more. End by annealing the part a final time.

The idea of having a fabricator bend a length of plate to the proper angle is an interesting one. Assuming that they don't just stick it in a brake and try to bend it in one shot, this might work. Or maybe the alloy of metal you have will take that...
Also, you might find that you want to vary the angle of the toerail as it runs along. The angle that your brackets set is the angle to the deck, which isn't the aesthetically or functionally significant angle. What people see when they walk by your boat is the relationship between the hull and the toerail.
Does it flare out? tumble in? I personally sort of like toerails that have some tumblehome, particularly up forward, where a toerail with a lot of flare is prone to getting banged, damaged, knocked loose when coming alongside a pier.

[George Ray]

Annealing Bronze ???
I have always thought that copper alloys 'QUENCH' to soften/anneal. Unlike iron that soften/anneals by SLOW cooling.
Googling a bit confirms this.

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http://museum.worldwidesam.net/reenactment/en/arms/roman/edgings-helmet.htm

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http://users.lmi.net/drewid/Annealing_bronze.htm

Q: I need to bend a thick piece of bronze, but it is too stiff. Any ideas?

A: This will be easier to do if the bronze piece is annealed first. While steel is annealed
by heating to red and being allowed to cool slowly, metals which crystalize in the
"Face-centered Cubic" system- which includes the copper alloys as well as gold and
silver- will reharden if they are treated this way. The crystals, given time, will form a
more organized structure, without the molecular "vacancies" which make the metal
malleable. In fact, one can take advantage of this tendency to "heat-harden" non-ferrous
metals, holding sterling silver, for instance, at 280 degrees C (536 F) for 2 1/2 hours.

To soften metals of this type, they should be brought to a medium red color, then
quenched in water to cool quickly. I would be careful not to overheat it though-
some bronzes will suddenly go from solid to falling-apart when hot. See Tim
McCreight's excellent handbook "The Complete Metalsmith" c. 1991 Davis Publications,
Worcester Mass ISBN 0-87192-240-1 for more details on annealing and hardening, as
well as other aspects of the hand metalworker's craft.

Andrew Werby

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http://www.metalartistforum.com/forum/showthread.php?tid=1071&page=1

Anneal....... a heating and cooling process used to soften and reduce internal stress in a material. Usually metal and glass. I'll concentrate on metal for the time being. The reason you'd want to anneal a metal would be so that you could increase the malleability. Making the metal easier to work cold. (i.e. forging, bending, twisting etc.)
Metals..........
Non ferrous metals(i.e. brass, bronze, copper, aluminum, silver and gold) are annealed by bringing up to a temperature that causes the "Grain structure to grow/enlarge" and then rapid cooling in water. There by "freezing" the grain structure at the Large size, stabilizing the metal at a annealed or "soft" state. Some non ferrous will experience the same annealing effect without the quenching in water. By air cooling. The temperature varies with the non ferrous metal. Brass, bronze and copper.........can all be taken to a soft red color and quenched. Aluminum doesn't show a "red" color at the annealing temperature. There are a few "tricks" to tell the proper temperature of aluminum. One is to use the Oxy/Acet. torch set up. First turn on and ignite just the acetylene. Use that acet. flame to "soot up" the aluminum. Then add the oxygen to the mix and start to heat the aluminum. Keeping in mind that aluminum is a great "conductor". When the soot burns off the aluminum, the material is at an annealed temperature. It can then be quenched to "stabilize" the aluminum at an annealed state. Another "trick" is to use a wooden stick.......like a paint mixing stick. Even the wooden handle on your hammer will work. The wood acts like a "temp stick" that tells you when the aluminum is at the "annealed temperature". As you first apply heat to the aluminum and rub it with the stick, the stick almost feels like an eraser on the warm aluminum surface. It drags and grabs, giving a sense of "resistance". As the temperature gets higher approaching the annealing temperature. The stick will leave a light brown line/mark as you rub the aluminum surface. And the color of the "line" or mark will get progressively darker as the temperature increases. Also......the sensation of the "eraser" effect will change. It will feel less and less resistant, sliding over the surface of the aluminum. At the point that the line/mark is DARK BROWN or even BLACK....the stick will seem to SLIP across the aluminum as if greased. BY practicing this method, even a blind person could tell if the material was at the correct temperature by the "slippery feedback".

NOW......ferrous metal(steels) will have the exact opposite effect if treated the same way. Meaning if you get the ferrous metal up to that non magnetic temperature and quench it........you will harden the metal which is the opposite of annealed.
To anneal ferrous, you still bring it up to a normalized temperature (a non magnetic state) At this high temperature the "grain structure" is larger. And to maintain, or stabilize the grain structure at this annealed or softened state the material should NOT be quenched. Instead the cooling process is slowed down, extended as much as possible. By "insulating" the hot metal with any material that will extend the cooling process, there by maintaining the large grained annealed state. I'm familiar with folks using lime, ash, hot sand, vermiculite, etc. Some will just leave the hot metal in their forge and cover it with coal. Turn the blower off and let it cool down with the forge. This isn't as effective as using something that has a greater insulating factor.

This is "readers digest" version .............great thread Matt.

[Cecil Borel]

Thanks for your responses, Gentlemen. However, if I may redirect, I am really interested in cold bending this stuff. I know it bends well cold. I am hoping that one of you could point me to someone who has a metal bender that I might borrow. Failing that, alternative suggestions are helpful and appreciated.

[Bob Smalser]

http://www.sawmillcreek.org/showthread.php?t=21337

http://pic3.picturetrail.com/VOL12/1104763/7652151/100594382.jpg

http://pic3.picturetrail.com/VOL12/1104763/7652151/100594739.jpg

http://pic3.picturetrail.com/VOL12/1104763/7652151/100594949.jpg

[TimmS]

I have bent metal parts like that with a rebar bender.... like this:
http://www.mccusainc.com/Tools/images/Rebar-Cutter-Bender-16.jpg
http://www.mccusainc.com/Tools/images/Rebar-Cutter-Bender-16-6.jpg

My dad builds houses so I have access to one. the only issue I see is that the bend radius may be too big for your application.

[Robert L.]

Cecil Borel post#10

Thanks for your responses, Gentlemen. However, if I may redirect, I am really interested in cold bending this stuff. I know it bends well cold. I am hoping that one of you could point me to someone who has a metal bender that I might borrow. Failing that, alternative suggestions are helpful and appreciated.

Cecil, yes you are correct, you do bend non-ferrous metals cold not hot. What the others are pointing out is that prior to bending, or during the process if the bend is complex or extreme (88.5 deg at that radius with 1/4" stock might be considered extreme by some of us who are more cautious.) you may need to anneal the material to make/keep it workable. Even straight from the mill it may be very likely that the metal has been work-hardened from the rolling, polishing, cutting etc. that it goes though before you get it. For sure drilling and countersinking the screw holes is going to harden it up. Annealing non-ferris metals isn't too hard or complicated from the standpoint of the small craftsman, and is way easier than working iron or steel. Fire up the BBQ in a shady spot. When it is ready to sear a steak start putting your pieces of bronze in one at a time. Let it get a dull cherry red in the bending zone then toss it in a bucket of water. After the first couple you will have a feel for how long it takes and can start loading them in faster. Don't over heat them and don't worry about getting the whole bar red. Once you have all the bars annealed, and it won't take long, you are good to go for bending them whenever it is convenient. Don't worry about knowing which end is annealed, it will look different. A simple jig should make it pretty easy to bend them in one shot. Number them and do a trial fit before brazing on the braces. If any need tweaked it is pretty easy to reheat and re-anneal them with a propane plumbers torch. Annealing non-ferris metals is easy and quick and way better than pulling and replacing the part when it breaks later from the stress cracks put in by working it un-annealed.

Good luck and happy boating.

[Canoeyawl]

Anyone with a press brake can do this cold (and easily)
You should know the ratio for minimum bend radius:thickness for your material.
(for example T-1 steel plate is thickness x1= r)

[Cecil Borel]

Great suggestions! thanks guys. much appreciated.

[seo]

Interesting comments on annealing bronze by quenching it. I'm going to try that next time I'm doing stuff with bronze. I've been cooling it in a bucket of ashes for nearly 30 years now, and have been able to anneal stuff successfully that way. Which isn't to say that quenching it won't be better.
However you go about annealing it, I think you'll find it necessary before you've put a right angle bend in a piece of 1/4" plate.
As a final note, you might discover that metal is cheaper and available in a wider variety of alloys if you buy it as 1/4" X 2" flat bar instead of in a piece 1/4" thick by 8" wide, which might have to be cut out of a piece of plate. It probably depends on the supplier...

[Cecil Borel]

I want to follow up on my post earlier this fall. In fact, I was able to get the flat bar bent to the 87.5 degree angle with a cold brake. Following the bend, I drilled the mounting holes, then TIG welded the brace rod in place. Final buffing in progress.

Thanks again for all your advice.
http://gallery.mac.com/cecilborel/100015/IMG_0268/web.jpg

[George Ray]

I am using high silicon bronze, C655 from atlas metals

Looks great, did you process/anneal the material or cold work as delivered from Atlas?

[Bark]

Looks great. Any photos of Janetess to share?

Ben

[Cecil Borel]

George: we cold worked the bronze all the way. thanks for your compliment.
Bark: I am keeping up the Janetess album at http://gallery.mac.com/cecilborel#100015, thanks for your interest

[bluedog225]

George: we cold worked the bronze all the way. thanks for your compliment.
Bark: I am keeping up the Janetess album at http://gallery.mac.com/cecilborel#100015, thanks for your interest


Wow. That is some serious dedication to a project. Looks great. Good luck.