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Help dishing brass sheet


MOblacksmith0530

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Okay I don't do a lot of work with brass. I have a request by a friend to dish a small piece of brass for a "targe". This is a shield for those not in the know. It needs to be about 2 inches in diameter, hat a 1.4 inch lip all around the outside edges. I haven't seen the brass they want to use but I would think not more than 16 gauge thick. I know it will work harden while I am doing this so I need to know how to anneal it. Copper anneals by quenching, does brass do this as well? I am thinking of making a form to sink it into with a heavy lip so that I can forge down this lip on the outside. It also has to have a spike mounted into the top of the dome portion and I am thinking about silver solder for that or maybe a tig weld.
Thanks in advance for any help.

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Depending on the strength you need, I would go solder. The center of the top will likely be very thin and hard to weld. All quenching does for copper is cool it off faster. Same with Brass. If your form is metal, you can start working it as soon as you have heated it to a very dull red or when the flame hitting the brass has a metallic appearance. This happens after all the flammable (oil, dirt, etc.) have burned off.

Good Luck

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I would like to see pics of this.

I would suggest making a threaded socket that fits under the "boss" the brass item you are making. Being able to unscrew the spike makes the targe easier to transport and store. Make a shiny knob to take its place, make it more friendly for renn fairs.

Nobody wants to go around with a hole in their targe do they?

Realy post pics of the finished peice!!
Cliff

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Make a wooden form for your lathe and spin it. It's the heating up that softens it you don't need the quench but it will speed up the process. A little vinegar in the quench will help the scale come off. Can you make a tenon on the spike and rivet it?

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Hmmm hadn't thought about spinning it that is a good idea. They don't want the spike riveted for transport reasons, I had already suggested riveting and they declined. They have a threaded base piece that I have not seen yet. When I get all the parts in a few weeks we will give it a try.post-24703-0-81772200-1334752133_thumb.j

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Ever spun brass? Brass is a lot harder to spin than most think, it work hardens quickly and if you don't know the feel of when it's going over you risk it coming apart in the lathe. Even scissor tool spinning is risky till you learn the feel and sound. Dishing or sinking is far safer and not a lot harder to do.

Annealing is a matter of bringing it to a low red and letting it cool, quenching just shortens the time till you can get back to work on it. Of course you can heat it to low red and work it hot. The trick Dad used to tell me for working brass and bronze alloys is, "Take it as far as you can on the first pass, you only get three." Basically you can move copper alloys as far as you can on the first push but it'll work harden to possible failure mode in three pushes. (beatings, spin passes, pressings, etc.)

Frosty The Lucky.

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You could make a wooden form for it and do die forming. Figure out the size of the disc you need to form the dome by taking the depth of the finished form and adding the diameter without the flat lip. Then add for the flat lip you want plus a little extra. Take this disc and screw it to the face of your form after you anneal it. Now you can form the dome and the lip at the same time because the lip will stay flat while you sink the center. Its very effective if you need something with a lip.

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Ever spun brass? Brass is a lot harder to spin than most think, it work hardens quickly and if you don't know the feel of when it's going over you risk it coming apart in the lathe. Even scissor tool spinning is risky till you learn the feel and sound. Dishing or sinking is far safer and not a lot harder to do.

Frosty The Lucky.


I'll drink to that!

I've got a bit of Bronze I want spin but I'm chicken because of my failure rate wth brass....
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I'll drink to that!

I've got a bit of Bronze I want spin but I'm chicken because of my failure rate wth brass....


You're using hand tools not scissor tools, yes? Use lots of lube, sticky is as important as slick or more so. When the blank starts to fight you, just stop and anneal it. Freshly annealed it'll move like stiff putty with no rebound to speak of, as it starts to rebound after your second maybe third pass you're getting close to stiff. As soon as you feel it start to fight, anneal it and start again.

Without scissor tools the high friction drag of hand tools compared to rollers makes for fast work hardening for much less progress. Patience will be rewarding. Bronze is a little more forgiving than brass for a given value for brass or bronze. Modern alloys have a lot of gray area in them so it's always ify unless you know specifically what you have. And no I don't, never did, know enough to say what alloy means what.

Ever thought about setting up for scissor tooling?

Frosty The Lucky.
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