Jingasa question

[Buster]

I've seen Jingasa that looked to be made by removing a wedge from a circle, the folding it into a cone.
Was this commonly done for iron jingasa, or was this more for leather ones?

[Destichado]

Actually, not nearly as common as I would have thought based on reproductions. Most iron jingasa were sunk from a disk or made from spangen construction.

[Buster]

That makes sense, since other Kabuto were usually made from spangen style construction.
But it's still a historically viable option, isn't it?

[Destichado]

Well, I saw one, but I'm really not the one to speak authoritatively.

[Effingham]

It's a viable option, but wasteful of materials. Plus, to make it a proper circle when formed, you'd have to cut around the perimeter again to return it to a proper circular shape.

[Buster]

Isn't it possible to cut the pattern in an oval shape, so that it makes a perfect circle when formed together?
I'm not good at visualizing patterns like this, does anyone know of a formula to calculate the needed shape?

[losthelm]

I would think posterboard would be faster... the math is not realy that bad just a bit of drafting then scaleing up for size.

The traditional rivited pannels lets you use a lot less steel and you can do some great gingerbread/file work on the lap joint.