Bending/shaping cast metal parts

[andy49]

What is the best way to bend cast metal parts like a trigger guard? Cold or hot?
Thanks!
Andy

[Hungry Horse]

 O.K., First, iron, or brass? Now is it really brass, or is it some kind of wax cast bronze? If its sand cast brass, or wax cast steel, you need to anneal it before you start bending. Brass is annealed by heating it to dull red, and then quenching it in cold water. Steel is annealed by heating it red hot, and burying it in warm sand , or ashes, until cold ( a couple of hours).
Bronze parts are hard to work with since different alloys anneal differently. I usually just avoid them.

            Hungry Horse

[T*O*F]

Brass is annealed by heating it to dull red, and then quenching it in cold water

Not true.  Quenching just cools it off faster.  It will anneal just as good by letting it cool naturally.

[jerrywh]

 It anneals softer if you quench it but the difference is negligible. I know. Who cares?

[Gary/CO]

When Gary Brumfield taught patchbox making, he had us anneal the brass by heating it with a torch and then quenching it in water.

My bench metal instructor at Trinidad State JC taught the same thing.

[David R. Pennington]

On iron parts do the bending while it is hot then bury in the ashes till cold and it will file easier. Brass parts sometimes can be bent cold. Go slow and carefully. Probably safer to aneal first. I have rifle with the triggergaurd spur silver soldered on. Oops.

[Acer Saccharum]

On bending, rather than use my fingers, I make a three-point system of hardwood blocks for my vise. Then you can focus a bend exactly where you want the guard to bend, and adjust the bend with complete control.

[jerrywh]

 A foundry supply once sold me a bar of silicone bronze and told me it was yellow brass. I cast some parts from it and found them to be very brittle. I was never able to anneal them. The experts say you can anneal it at 1200 to 1300 for 5 to 8 minutes and then quench them. It never worked for me. They would not bend hot either. 
 My suggestion is to anneal them like brass. If they still seem springy don't try to bend them. Yellow brass will bend with little effort when annealed and is not springy at all. Also Bronze doesn't oxidize as bad as brass. If you heat it to 1300 and it is not very oxidized that is an indication that it is not brass.

[andy49]

Thanks everyone for the input. I am dealing with cast iron. It seems to be harder than regular sheet steel and feels like it could easily snap. I think annealing first is the answer.
Andy

[E.vonAschwege]

Andy - if you bought the parts from a reputable supplier, they will not be cast iron, but cast steel  .  You may still need to bend the steel while hot.  No amount of annealing will anneal cast iron, it will just crumble.  I bought some cast triggers once and while red hot I began pounding one out - it broke into a pile of crumbs.  I like Acer's diagram for bending.  Using a vise and forms make bending a controllable and more precise maneuver and takes most the guesswork out of "that feels about right" when doing it by hand. 

[T*O*F]

Andy - if you bought the parts from a reputable supplier, they will not be cast iron, but cast steel

Conversly, if you happened to buy them from Dixie Gun Works, some of their older parts are cast from a slag of old beer cans, rusty wire, and various other scrap steel.  They will snap if you look at them cross-eyed.  I try to buy only steel parts that have been investment cast as they are usually better and more recent.

[andy49]

Eric, you are right it is cast steel and I used Acer's bending jig which worked perfect.
Andy

[WadePatton]

I had no problems bending my cast steel guard hot. 

But I had been warned by the vendor that some of the cast steel he sells won't bend cold.  I promptly forgot which was which, so I heat it all.  But then I like fire and steel.

My next few guards came from a different source.  I'll heat them too.  Mmm, warm metal. 

Everyone should study up on alloys and heat treatments a little bit. 

It's not magic, it's metallurgical physics. So the next time they ask you what you've been up too, you could honestly answer "practical exercises in metallurgical physics".

That should draw some blank stares.

[Mark Elliott]

I have a simple rule; iron or steel is bent red hot, and brass is bent cold after annealing(heat to dull red, let cool to black and quench(so that you can work with it right away)).   If you have bronze or cast iron,  it will break no matter what you do.  When it does, get real yellow brass or steel.    Reeves Goehrings castings come dead soft and can be bent at a given point once before annealing that point again.   I prefer to bend soft brass with my fingers.    Hot iron/steel I use a a vise(or ViseGrips) and needle nose pliers.   

[bama]

Brass i anneal, the way i learned was to coat the part in candel soot and heat until the soot burned off and then quench in water.

Steel should heated to at least an orange heat and bent while hot. You can sometimes get away with a cold bend but if the part feels springy you are taking gamble. I would rather heat than solder or weld to repair a break.

[JCKelly]

Brass mUST be bent cold, not hot. It will crumble if bent hot

This is true whether or not you anneal it first.

Steel bends best hot, personally don't believe it has to be orange hot.

Decades and decades ago Dixie Gun Works sold cast malleable iron stuff. Don't know if they still  do. Cast Malleable iron, in spite of having some ductility, is likely to crack when bend cold. When it does, the fracture surface will have little black dots on it. They are the graphite "rosettes"