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 Post subject: Re: Almost there, helmet cont.
PostPosted: Wed Jan 22, 2014 10:37 am 
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dragnfly wrote:
Wouldnt you want some padding in there??


downunder "Now a few epoxy coats and with a PU varnish, some EVA inside or even neoprene, strap and that is it! Hoping for less than 220g. Light as feather"!
downunder wrote:
plummet wrote:
looks a bit wrinkly at the back?

swap the Double bias glass out of 1/3 weight db carbon and booya! sub 200G.

Dammit maybe I need to make my own helmet.

PS. Good choice of carbon/Kevlar. that will give you good impact resistance and strength.

PSS Have you considered that there may need to be a certain amount of flex in the helmet to absorb the impact? Super stiff may transfer the force rather than absorb it?



It's got channels at the back which makes it extremely difficult to make it perfect. The inside is fuuurfect. Which makes me think to reverse the mold to a female one. Easy peasy.
For a first run I am more than happy. A few epoxy coats and won't be visible:)

There is a flex, no probs with that. There will be more of it when cut to a final shape with more open forehead, like ie. Gath. The idea is a skin helmet, tho. With the ears protection as well (a new mold).

The absorption should come from some inner linings, foam, eva, etc.

Cheers for suggestions. Duno how to finish edges which are sharp now?

Do it! You know you can!


This looks awesome, Is there any thoughts of drainage holes, so it doesn't bucket?


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Wed Jan 22, 2014 3:08 pm 
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Yes, thanks for asking.

One might do it beforehand or after epoxy. Before might be easier to cut in desired shape. Thinking of "tears" shape:)


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Fri Jan 24, 2014 2:52 am 
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Plummet asked:
' Have you considered that there may need to be a certain amount of flex in the helmet to absorb the impact? Super stiff may transfer the force rather than absorb it?'

I wondered the same thing, and it needs some foam sandwich core to crush under this bulletproof (amazing!) skin. Maybe it's in there but I can't see any? I have some 1/8" or 5mm? Divinycell that seems soft enough to perhaps be the impact absorbing layer you are speaking of. (I don't want to wear a giant space helmet so just the bare minimum). It's the super light density stuff that is very very flexible and feels crushable too. A very thin sandwich of light carbon kevlar outside and a very minimal 4oz fiberglass inside to get a shell that is going to absorb the typical kite-surfing accident of board hits head. I have no idea how to get that all in a vac bag in the desired shape of my head though, and couldn't quite see how you went about it. Incidently, I notice few SUP paddlers use helmets but they should with such a heavy board bouncing around in the surf, and so too all the surfers diving for cover inside the kiters and SUPers..... They do wear all sorts of funny hats for sun protection. A sun hat with just a bit of impact absorbtion/protection would be ideal for many advanced kiters and surfers. How would you make that? Not to hijack this excellent thread but that crushable foam layer has not yet been addressed here in this 1st edition, or maybe I missed it? I noticed it had been discussed previously. Much thanks to the original poster Downunder and what a great job so far! Getting inspired :thumb: .


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Wed Mar 12, 2014 12:50 pm 
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Rebooting the helmet project :thumb:

After I've finished a new board for myself ( http://www.kiteforum.com/viewtopic.php?f=107&t=2383984), decided to make something to match it. You guessed right - zebra veneer.

The idea is to build it with a FG first, check the size, adjust if needed (this one was too tight), and than go with the real thing - kevlar and a veneer.

Also, adding more "meat" on my plaster mold to cover for ears protection.


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Fri Mar 28, 2014 5:49 pm 
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I'm not sure if you did much googling on how to make a helmet, but while looking at something completely unrelated, I saw this video along the side menu, and immediately thought of this project. I wonder if you could do this same thing with corecell, or whether you could glass something like this?
:)

http://www.youtube.com/watch?v=ODSNPYdvJRo

Peter


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Sat Mar 29, 2014 2:56 am 
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Interesting, thanks for posting.

This should be easy to make from this video. To make a shell is not easy tho. Wrapping the kevlar in one go and not getting any wrinkles I think is the main problem.

I think this might be easier IF not doing a complete helmet, ie the Gath shape. This is what I'll try next.

Cheers

D.


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Sun Mar 30, 2014 6:15 am 
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Not sure if you are familiar with helmet testing procedures but making a helmet too strong is just as dangerous as not making it strong enough. Even if you are borrowing pads from other helmets you're basically making something that could mess you up almost as much as not wearing a helmet.

http://www.pinkbike.com/news/Video-Helmet-Safety-Comparison-2012.html

Watch the video, Bell kinda knows what they're talking about.


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 Post subject: Re: Almost there, helmet cont.
PostPosted: Sun Mar 30, 2014 12:20 pm 
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NorCalNomad wrote:
Not sure if you are familiar with helmet testing procedures but making a helmet too strong is just as dangerous as not making it strong enough. Even if you are borrowing pads from other helmets you're basically making something that could mess you up almost as much as not wearing a helmet.

http://www.pinkbike.com/news/Video-Helmet-Safety-Comparison-2012.html

Watch the video, Bell kinda knows what they're talking about.


Hm. No, you got it wrong. The current shape is strong, but after cut into a desired shape it will be flexible.

Take an egg or a ping-pong ball for example, or a half sphere. It is strong but when it's cut like an orange not strong any more.

Also not correct with "borrowing pads" since almost all water helmets are padded but glued. Not possible to take out. The "white water" kayaking helmets are not padded, they are more like a climbing helmets.

Many skydiving helmets are carbon cevlar and Hiko in the EU made heaps of kevlar helmets for a "white water" as well.

Lastly, we are dangling on a 25m lines. Certified? Not. Even a scuba tanks must be tested each year:)

I like Australia where the bicycle helmets are compulsory by law. And than Holland with 13mil bikes has no such a law and less ppl die while riding...Even Schumacher is still in a coma, remember?

Helmets do not protect from broken neck. Ideas? Please do share.


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