Metal Working Question


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Wwalstrom
February 27, 2007, 11:52 AM
HISTORY: Last fall, I was able to scavange some pieces of 1/4 diameter brass rod from work. I had access to a Grizzly Mini-Lathe, and made a pocket cleaning rod set ... I had 3 pieces trimmed and cleaned up with #8-32 taps in both ends, and one 2 inch peice that I tapped one end #8-32, and threaded the other end 1/4-20 for a big Plastic T-handle that I had scavenged years earlier. All of this, along with a jag, brush and a patch loop will fit into an altoids tin (i.e. - pocket/possibles bag sized). I like the kit, it works well, but does take some futzing around with to get everything to fit in the tin ... mostly due to the fairly large plastic T-handle.

I'm looking to start making a presentation box for my stainless revolver in the spring, and had thought that a more period correct version (with a slightly modern twist) would be nice. The rods I plan to duplicate would be the ones with the end bent into a round/teardrop shaped loop. I would still plan to segment it, to fit into an altoids tin I'm working on antiquing ... but I need help with the bending part.

This time I plan to use 5/16 diameter brass rod. I managed to scavenge a piece to play with, and figured I needed to heat it to bend it. I heated the end to a nice cherry red, and bent it around some large pins clamped in a vice, and it worked very well, until I dropped it (a 1 foot fall) onto my workbench ... and a full 1/2 inch fell off of the end! The end looks like it crumbled, if that makes sence, a really rough, jagged break. Imagine my disappointment.

Did I apply too much heat? Should I have quenched it in water or something? Where did I go wrong? Any help or suggestions are welcomed!

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Loyalist Dave
February 27, 2007, 12:22 PM
I have been told, that when you heat treat brass, and let it cool slowly, it gets brittle, but when quenched in cool water, it's soft. Just the opposite of iron or steel, which when cooled quick get brittle, but become soft when heated and allowed to cool slow.

LD

Steve499
February 27, 2007, 12:50 PM
Steel becomes harder when heated red hot and then quenched, and is most plastic and therefore easiest to work, at a high heat. Brass, on the other hand, is made softer and more malleable after being annealed, which is done by heating and quenching it just like steel is hardened. Brass becomes harder as it is being worked, eventually becoming brittle, and is best worked cold. Heated brass will crumble easily if you try bending it while it is hot. If you wish to bend a brass rod, anneal it and bend it part way. Anneal it again and bend it farther. I suppose there are all kinds of different alloys with brass-like appearance which may behave a little differently depending on their composition, but, as far as I know, they will all behave more or less the same.

Any heat treating process on metal which isn't done to the entire piece, as in heating the tip of a rod, for example, can cause problems at the area where the hot transitions to the cold. When quenched, that area will possess all the range of properties, from brittle to soft, and can be a point of failure. If you have a soft brass rod with only the tip work hardened, though, as long as you heat past the work hardened area and quench it, you should restore the entire piece to it's soft condition.

I suspect the rod you dropped broke while it was still hot at the point of the break. That crumbly look generally means a hot break in brass.

Steve

Aries-
February 27, 2007, 07:34 PM
brass is best bent cold. no heating required.

not sure how you would go about bending it to a teardrop. id guess something with a vice. or a custom bending table.

Coyote Rider
February 27, 2007, 08:12 PM
I agree that brass is best worked cold. I would try bending the rod using an improvised jig something like what it sounds like you already tried. Or you can try smacking it with a leather mallet around a proper-sized steel rod or jeweler's ring mandrel. You may not even need to anneal it first. If you find that it needs to be a little softer then go ahead and heat it to a dull (not cherry) red. You can let it cool by itself without quenching it--I have a dim recollection of having learned at one point that quenching soft metals weakens them a little, but that may be bad intel. I do know, however, that it's not necessary.

4v50 Gary
February 28, 2007, 12:07 AM
Bend the brass cold, then heat it to anneal it. That's what I was taught in the brass patchbox making class.

Tbu61
February 28, 2007, 12:58 AM
The above posts are somewhat correct, Steve499 is most accurate. Heating and rapid quenching of Brass (annealing) cause the Brass to "soften". Ferrous metals (Steel and Iron) react differently to the process.

Do the annealing prior to bending.

Brass only needs to be heated to a uniform dull red color, then doused into cool water. Bend the rod after it has cooled. Repeat as needed for compound bends.

Annealing does not make the Brass any "weaker", it just makes it amorphous or softer.

Working, (flexing or bending the Brass) causes it to become stiffer. The metal structure becomes crystalline, stiff and brittle. Heating and slow cooling will also stiffen the same piece.

The exact same is true with some types of shell cases that are frequently resized. The necks become brittle and split upon firing. Annealing them adds to the lifespan of the case. I once had a large quantity of .30 Remington cases, the first 20 I loaded ALL split. I annealed the remaining 200+ cases and NONE of them have failed.

Annealing works, it's simple metalurgy......

tbu

Coyote Rider
February 28, 2007, 07:07 PM
Tbu61's info sounds right. The only thing I'm not sure about is heating and slow cooling causing hardening. I'm sure I've heated and allowed silver to cool by itself, and it stayed soft, and I believe it should be the same for brass. However, I haven't done any silverwork for a few years, and I'm not getting any younger.

Hmmm. Let's see. The older I get, the more my thoughts turn to the hereafter. Like I'll go into another room, and I'll say to myself "What am I here after... ?"

Aries-
February 28, 2007, 07:20 PM
every ferus and non ferus metal acts differently.

Silver isnt going to act the same as any of them. silver is a virtualy pure metal and soft by most standards. brass is a combination of copper and zink, so its going to act different than bronze which is copper and tin(?).


ferrus metals all are easyer to figgure out yu heat them to a point and they harden. (some at a lower temp than others)

non ferus are way harder. i have my machenists handbook around somewhere i could list them all but it would take a long time lol.

doubleh
March 1, 2007, 01:45 PM
Most of the stuff called brass today is actually manganese bronze which is much stronger than brass. Both of them exhibit a condition called hot shot which means they become brittle and break when worked hot. Some steels also have this problem. To anneal brass and bronze heat is to dull red and allow it to cool,. Quenching in water or cooling slowly makes no difference. They will harden when worked.

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