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  1. #1
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    Default Sheet Metal Dome

    Hello all,

    Over the last little while a friend of mine has been building costumes for her conventions, and she's wanted to do something like this:
    Imgur: The magic of the Internet
    I've been helping her make the costumes off and on, and she wants to make this one. My question is how would you guys go about making the top of the helmet in the red circle in the second image? I've only had a little work with sheet metal and I've just bullied it into the right shape with a hammer usually. What I'm looking for is a way to make a large radius half-sphere. As for materials, brass is too expensive so I'll probably make it out of aluminium and paint it up proper or let her do that.

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    large radius half sphere ?

    Salad bowl ?

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    I'm mostly asking how someone would go from a flat piece to a dome, more out of curiosity than anything.

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    Quote Originally Posted by KevinPartner View Post
    I'm mostly asking how someone would go from a flat piece to a dome, more out of curiosity than anything.
    I'm PRACTICAL MAN....why not try explosives ?

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    I have done this, but you wont really like the answer.
    The way you do it is, you special order a 3000 series soft aluminum sheet. Then, using a shot filled leather bag and a rounded mallet, you rough shape it, then you smooth it out with an english wheel, then you repeat as needed to get the right shape. The learning curve is a few weeks, if you are already handy with sheet metal.
    If you really want to learn, I suggest starting with the late great Ron Fournier (my teacher) and his book, Metal Fabricaters Handbook.
    Its all in there.
    Metal Fabricator's Handbook: Ron Fournier: 75478874: Amazon.com: Books



    What you should do instead is use vacu-formed plastic domes, which are available at most costume supply stores, made from thin poly.
    Hot glue em, cut em with a mat knife.

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    Metal domes are often spun (watch Youtube for Spun Metal) but you don't really have much of a dome there, it's more of a heavily filleted cone. The method Reis describes what armorers use and that is what you need here since it's actual (fantasy) armor. With these methods you can get the whole shape from one sheet if you are skilled. But yes, you'd have to think vacuum forming plastic would be the way to go if it isn't intended to be actual fantasy armor. But rather fantasy fantasy armor.

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    This may be of interest to you.

    Hydroform - YouTube

    Hydroforming a dome shaped part using grease gun pressure. Project prep is a machinists dream.

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    I think the device that you want is called an English Wheel.

    English wheel - Google Search

    https://www.youtube.com/results?sear...+metal+shaping

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    I know you said you wanted to make it yourself,
    but if time is money, you can buy a steel hemisphere
    relatively cheap:

    12" diameter Hollow Steel Hemisphere. .118" Thickness, 12" Outside Diameter with a Single 1/8" Weep Hole, 5.8 lbs.

    8" diameter Hollow Steel Hemisphere. .118" Thickness, 8" Outside Diameter with a Single 1/8" Weep Hole, 2.7 lbs.


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