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Modeling in General: Advice on...
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Annealing Photoetch
Bigskip
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Posted: Monday, December 11, 2006 - 08:27 PM UTC
Hi there

I keep reading that it is better to anneal your photoetch before trying to bend it by heating to red hot and letting cool naturally, and i understand the process having studdied Metalwork at school, however i am unsure of the best method to heat the etch.

Would a blowtorch be the best way, or would the direct heat cause a problem?

Thanks in advance.

Andy
Teacher
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Posted: Monday, December 11, 2006 - 08:35 PM UTC
Andy, a blowtorch is far too powerful! Even a cigarette lighter will do. Get it glowing red and then quench it in cold water. This is only necessary if you're going to bend the part into a curve. Normal bending of PE does not need it. Some people let it cool down to rooom temperature by itself, and this slow cooling is probably important when annealing larger quantities of steel, but with PE I've never had a problem water quenching.

Vinnie
Bigskip
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Posted: Monday, December 11, 2006 - 09:59 PM UTC
Cheers Vinnie.

I have a couple of pieces i need to bend in a curve, so will try to find a lighter from somewhere. I threw all mine when i gave up.

Andy
jlmurc
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Posted: Monday, December 11, 2006 - 10:15 PM UTC
Andy,

As we cook on gas, I just pass it through a low flame over the cooker, I do allow to cool at room temp but as vinnie says for small bits water quenching will do. On large bits using water can cause thr metal to cool a very different rates as it enteres the H20 and that may make it crack when you bend.

I used to anneal a lot when helping a friend who had a jewellers shop and workshop.

John
troubble27
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Posted: Monday, December 11, 2006 - 11:46 PM UTC
HI Andy,

When I anneal photo etch, I simply use a cigarette lighter (specifically a Zippo), and let it cool at room temperature. It is so thin that it heats up fairly quickly and also cools fairly quickly. I dont bother putting it in cold water, and I only anneal parts that have to be curved. Parts that require striaght bends fold very easily without annealing, and I generally find it to be a waste of time. Go get yourself a disposable lighter, and you'll be all set.
mongo_mel
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Posted: Tuesday, December 12, 2006 - 12:11 AM UTC
Andy, a candle should work just fine for annealing the parts. With parts as thin as our PE pieces usually are, i think the blowtorch would be overkill.

Guys... I'd suggest that you avoid quenching the part in water. Quenching is specifically used to harden the metal.
Even (maybe especially) with small pieces, I'd think you build back in the chance of having the piece fracture by doing this.
One thought would be to get the part bent to the desired shape and then heat and quench. This might be worth doing if the piece is in a position to be easily damaged. Then you'd at least make it a little bit stronger.
Just my 2 cents
Craig
Bigskip
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Posted: Tuesday, December 12, 2006 - 01:22 AM UTC
Thanks to all

I did think the blow torch was a bit overkill - but you can never have too much overkill can you :-) :-)

Think it'll be a candle or a lighter if i can find one.

Andy
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Posted: Thursday, December 14, 2006 - 01:56 PM UTC
I too agree on the subject of not cooling the PE in water. At least steel is hardened that way and I suspect it might make brass harder and more brittle.
I would recommend using a lighter for heating PE, as using a candle may blacken the parts.
Usually I anneal parts that are to be rolled into tubes or other similar tricky shapes. I also found out that PE parts made of steel are much more pleasant to bend if annealead. Steel tends to spring back to original shape unless heated.
mongo_mel
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Posted: Thursday, December 14, 2006 - 05:57 PM UTC
Eetu,
You're right, the candle will blacken the brass. I never thought to mention that. Thanks for pointing it out .
But I've not found this to be a problem. On bigger pieces I just remove it with steel wool. On the smaller pieces i leave it. The primer seems to stIck to the blackened surface with no problems.
Cheers,
Craig
mat
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Posted: Thursday, December 14, 2006 - 06:29 PM UTC
Hi,

I have had some bad experiences with heating PE. If I made a mistake with CA glue I used to burn it of with a lighter. When I did that too often for the same part it would burn away. So don't use a blowtorch I guess....

Matthijs
airraid
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Posted: Saturday, December 16, 2006 - 06:35 PM UTC
As a general rule for annealing metals.

For Non Ferrous metals ie:- brass ,copper , to soften you heat and quench as they generally work harden.

Ferrous ie:- steel you heat and allow to cool naturally as quenching hardens the metal.

When I first started work I trained as a sheet metal worker and the above is what I was taught.

Hope it`s some help
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