I annealed 2 small bars of the same copper stock and vibrated one for about 12 hours and left the other on the shelf. The difference in hardness and the ability to bend or file the vibrated piece is profound.

Corehog

Copper does not age harden but some copper alloys do.But you would have to get it to the right temperature . Work hardening can be done by rolling, hammer,needle gun, shot peening , and some high tech things like laser peening .Some of these will only work a thin surface layer.

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You almost had it Daniel, it's called a needle gun Welding suppliers might have one, but I've only seen them as air tools, and not in an electric variation.

Walter

don't know how that tool is called actually (neither in german nor in english)... but usually it's being used to nock of the glass-like "slag" on weld-lines ... or nock loose oxides off...

I spent the weekend finishing a sword fitting....a habaki to be precise. After making them by cold forging and then brazing them shut the heat from brazing usually anneals the copper and it ends up dead soft.

me too, I've only seen the air-pressure powered ones... but a small compressors most of us have in theirs shops, so that should not be the actual problem...

Carbidedrills

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Harvey Tool

I guess that was really my question...are there better ways to harden copper than beating on it. I suspected I had found a better way and this morning I know that I have. It works along the lines of the shot tumbling method you were describing.

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Thanks for everyones input on this! And if you are in need of work hardening copper without deformation you might give Dennis's tumbler idea or the makeshift vibrator idea a try. Heck, with a little imagination we can come up with all kinds of stuff that will stand in for vibration.

Usually the hammering to get the fitting back on the blade and a deliberate amount of light hammering is used to work harden the piece and get it to fit exactly.

well I've never tried it on my own... don't have such a toy... and depending on the state of the copper you have to be carful not to mar the surface, unless you will grind a bit anyways... but it seems like an easy way.

They shot peen rotor blades to give them added strength and resilience so I guess the answer is even light, surface peening will create the change and work harden material.

Some minor scuffing of the copper is evident (steel shot would be less abrasive than the glass and might eliminate the problem) but essentially I have literally work hardened the copper without significant deformation. I may continue to experiment with different frequencies and higher intensity levels (higher frequency/more volume = more energy transferred to the copper and more repetitions due to higher frequency) and see how hard I can get it in how little time. Good stuff!

Brian, Coming from the exerience I have had in jewelry making. We encounter the same problem, annealing during soldering, and the fix for it is a simple machine... the tumbler. Looks like a rock polisher, some use them. Instead of grit you sub stainless steel shot of differing shapes. With this you get no surface change but in around 24 hours depending on the material it will work-harden nicely. Rio Grande sells shot, machines, liquid (for lube) etc. Hope this helps.

Helical

Yet it is definately springy and noticeably harder. I'd love to use this soft hammering technique or even just a period of high frequency mechanical vibration to harden copper but I'm not sure if it really worked or the minor hammering during final fitting did all the hardening.

This particular fitting was *sooo* close to a perfect fit that very little hammering was needed to correct the final fit. So I finished the fitting with hundreds of little, teeny, tappy taps that did not appear to deform the copper at all.

I just packed the copper in a small box with glass beads and set it on a 15" speaker cone reinforced with a piece of sheet metal and then hooked up an audio generator to the input of an amplifier and turned up the volume (I used a 60hz signal) until the box started to rattle nicely and left it all night.