Question about Annealing Copper

[ron]

Hi All
A couple of questions about annealing copper, I did an experiment today using a piece of 1/8" copper sheet, using a Coleman petrol camping stove as the heat source I could heat quite a large area of it to dull red in poor light, is this hot enough, it has annealed the copper to some degree or would I be better trying for a higher temperature.
Is it better to quench the hot copper or let it cool naturally or does it make any difference.
Thanks,
Ron

[Nexuas]

I is not the HIGHER temperature which improves the annealing process, but the amount of time that the metal remains at the temp. I think just before Dull red is the point you need to pass, then keep it at this for about 3 - 4 minutes, then quench in water then pickle, then bash and repeat as needed...

[the_viffer]

Quenching is not necessary for copper. The important bit is getting it hot. It can cool as slowly as you like and in my most humble Uriah Heepish opinion the slower the better to save on even more distortion.

Back to the dog house. Had a most amusing week in France avec la Taxi noir (pics here s118.photobucket.com/albums/o97/the_viffer with a steam bonus for those with nothing to do). Came back to pacify 3 Horses and then to be laid low by some man-flu. Today first day back at work for 2.5 weeks and just nipped out to buy flowers to try and calm the savage breast.

Cheers!

[paul]

My favourite part is the bashing

What an odd series of pictures the_viffer! I myself can be seen *driving* a tank engine into Chasewater station with a coach and a DMU (!) in tow here ... www.artefact-rescue.co.uk/glory.wmv (right click and 'Save as')

(How cool is that? )

I also have some steam pics from this years holiday 'sur le continon' ... very odd loco-Francaise!

[havoc]

Just let it cool, no need to quench I don't pickle if I have still forming to do. Just wipe the worst off with a rag. You probably need to heat it again anyway.

[houstonceng]

It's not really recommended to form the copper after heating - especially if you've let it cool slowly - without pickling first.

You risk hammering Copper Oxide into the metal which could affect it's strength and solderability.

[ron]

Thanks for the info, I hadn't thought of pickling it but it makes sense, I also got the impression the surface was coated with something the way it initially reacted to heat.
Err, I wasn't going to bash it, I'm going to skillfully manipulate it into a more useful shape with a large hammer and dolly---------------------------I hope ;D
Ron

[chris vine]

Hi Ron,

I find that copper "seems" to be the right temperature when the colours chase around under the blow lamp. I like housonceng's comment about not skillfully manipulating copper oxide into the part.

Private message to you as well.

Chris.

[the_viffer]

paul said:

My favourite part is the bashing

What an odd series of pictures the_viffer! I myself can be seen *driving* a tank engine into Chasewater station with a coach and a DMU (!) in tow here ... www.artefact-rescue.co.uk/glory.wmv (right click and 'Save as')

(How cool is that? )

I also have some steam pics from this years holiday 'sur le continon' ... very odd loco-Francaise!

Tres froid, Paul. Shame there wasn't more. Feel free to share any you have got.

The pics are odd because I am odd.

I also took the precaution of using a body double so I doubt I appear in any of them.

I'm all for bashing (esp after the row Erin and I have just had. I think there is a new Ice Age starting chez the_viffer) but bashing for purpose is better than bashing flat so you can anneal to bash into the shape you want once you have bashed the umps and ollers caused by the annealing out.

Citric acid is good btw for getting the black scale off annealed copper and much better in my mind than thermal shock which never completly works in my experience.

Once more into the breach...

[GWRdriver]

My preference is to quench (in cold tapwater). This achieves two things, it allows me to return to copper bashing in a few moments rather than and hour or so, and the thermal shock of quenching, which doesn't harm the metal, blasts away 95% of the copper oxide and no further treatment is necessary.

PS - Metalurgcally speaking there is no working difference between water-quenched copper and air-cooled, I simply prefer quenching.

[Steve M. W]

Now then when I read up on how to go about flanging my boiler plates for my Simplex and after speaking to other people who had built boilers, no article or person said anything about pickling after each manipulating (bashing) session so I haven’t.
I was however warned that the copper will work harden as you shape it and that to carry on without re-annealing it will result in cracks, this I was careful not to do and found that you could hear the metal hardening as you worked it so it was easy to know when to re-anneal.
Your comments please.

Just as an aside many years ago I was advised by an experienced engineer listen to the metal it will tell you if something is wrong and I have found this to be true in all aspects of machining and metal bashing.

Steve
Reposted from Simplex link

[baggo]

Steve,

I must admit I never bother pickling during 'bashing' and annealing operations and, like you, I've never seen it recommended in any books etc. Doesn't mean it's not a good idea though. Personally I want to get the job done asap and couldn't be bothered to wait for the copper to cool and then pickle it! The flanged plates that came with my Simplex boiler kit certainly hadn't been pickled. As GWRDriver says, if you quench the copper straight away most of the oxide etc flakes off and the copper comes out quite clean. Anyway, it's a good idea to roughen the flanges with a file before soldering as this helps the solder bond to the copper.

I find the number of times you need to anneal depends on the complexity of the flanging. The tighter the corners etc. the more you'll have to anneal. Interesting point about listening to the metal. Sounds a bit barmy at first but, thinking about it, the 'tone' of the metal will change when you hit it as the metal gets harder. It will 'ring' more the harder it gets.

John

[GWRdriver]

How very true that the number of times you need to anneal depends on the complexity of the flanging. I have found that the hammer (or mallet) will tell me when re-annealing is required and it will begin with the "second" blow and with each blow the metal will move less, or only with quite a bit more force in your blow.

I have found that a conventional 90 degree fold, as in a typical boiler plate, in 1/8" plate takes three annealings, sometimes four if I feel there is a bit too much resistance in the metal. The photo here, of the throat sheet of my 2X TICH Belpaire boiler, which can be seen in the photos I've posted elsewhere on the board, took nine annealings IIRC. This was 1/8" material. I could perhaps have done it in less, but better safe than sorry and ther results were very satisfying.

[paul]

...and I thought bashing over a simple flange was tricky! What sort of former did you use for that ?

[GWRdriver]

Two forms are needed . . . . a male form, for which the basic main flanging plate was pressed into service (as the backing plate) and a female form. I didn't want to pierce my back former because it's probable I'll need to use it again in the future. The two plates were clamped in a sandwich with the copper and I began the inside flange by carefully "picking" at it working all around with smooth wedges which slowly lifted it from the flat until it was at about 30 degrees or so at which point I could get at it with a hammer and a radiused forming block, sometimes called a "dolly" in the US auto body trade. I annealed regularly and it layed over just nice as you please.

[paul]

I see! Excellent, thanks for the explanation