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 Post subject: Helmet build
PostPosted: Wed Sep 25, 2013 3:36 am 
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Location: Perth, Australia
Hi all

in the light of recent tragedy in Perth I've decided to make a helmet for myself.

As a skilled board builders, would you have any tips for making a helmet?

Just finished a plaster mold head (close:). Than I'll use a hot vinyl to wrap the mold and seal it.

Was thinking to do epoxy infusion to keep the weight to minimum. Triax FG + carbon-kevlar biax cloth x 2.

Something like a "skin" helmet...Some foam inside + velcro from a cycling helmet.

What do you think?
thx
D


Last edited by downunder on Wed Sep 25, 2013 6:19 am, edited 1 time in total.

{ SHARE_ON_FACEBOOK } { SHARE_ON_TWITTER } { SHARE_ON_ORKUT } { SHARE_ON_DIGG } { SHARE_ON_MYSPACE } { SHARE_ON_DELICIOUS }
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 Post subject: Re: Helmet build
PostPosted: Wed Sep 25, 2013 4:02 am 
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Sounds good. I would ditch the glass and run all carbon and Kevlar.
high density foam and look into the neck clamping mechanism on mountain bike/roadbike helmets. they seem to be well ahead of the very basic surf/kayak helmets available.


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 Post subject: Re: Helmet build
PostPosted: Wed Sep 25, 2013 7:37 am 
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plummet wrote:
Sounds good. I would ditch the glass and run all carbon and Kevlar.
high density foam and look into the neck clamping mechanism on mountain bike/roadbike helmets. they seem to be well ahead of the very basic surf/kayak helmets available.



Thanks man,

what to you recon how many layers C+K if not using a FG? For a decent strength!


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 Post subject: Re: Helmet build
PostPosted: Wed Sep 25, 2013 9:19 am 
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downunder wrote:
plummet wrote:
Sounds good. I would ditch the glass and run all carbon and Kevlar.
high density foam and look into the neck clamping mechanism on mountain bike/roadbike helmets. they seem to be well ahead of the very basic surf/kayak helmets available.



Thanks man,

what to you recon how many layers C+K if not using a FG? For a decent strength!


I don't know.

Troy lee d2 carbon is the rolls Royce of dh MTB helmets. If you can lay your hands on one of those and measure it.

My gut says
1mm
Maybe 1.5mm? I really I don't have any reference.


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 Post subject: Re: Helmet build
PostPosted: Thu Sep 26, 2013 9:19 am 
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From F1 helmet construction:

http://www.formula1.com/inside_f1/safety/helmets_hans_clothing/7438.html

"The outer shell has two layers, typically fibre-reinforced resin over carbon fibre. Under that comes a layer of aramid (usually Kevlar®, the same material used in many bullet-proof vests). Then there is a softer, deformable layer made from polyethylene (a plastic based on polystyrene), covered with the same flame-proof material used in the driver’s overalls.
.
.
Did you know …that despite the cutting edge materials used in their construction, Formula One helmet liveries are still painted by hand? It’s an incredibly skilled job requiring hundreds of hours of work for more complicated patterns and designs."

Finished casting. Hope this weekend to vacuum it.

Not easy tho:

http://www.fiberforge.com/documents/Hybrid-Thermoplastic-Composite-Ballistic-Helmet-Fabrication-Study.pdf

To stop Kevlar or Carbon wrinkling (imagine 39 plies):

Attachment:
helm.jpg
helm.jpg [ 38.74 KIB | Viewed 1778 times ]


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 Post subject: Re: Helmet build
PostPosted: Thu Sep 26, 2013 9:40 pm 
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Maybe this is all figured out, but let me just throw out some thoughts here. What are you going to use for energy absorption? The carbon and Kevlar will work for protecting from impacts from sharp things like board corners and fins, but if you whack your head on a smooth hard surface, like pavement, that skin will do very little. If the foam is too soft, it will feel cushy in a minor impact, and bottom out and do nothing in a hard impact where it really matters. Like setting your bike suspension way too soft, and landing it hard.

Look at the hardness of foam in bike helmets, and that's probably what you need for good protection in a serious impact. Then again, you might get away with something a touch softer since you have a stiff shell on the outside, able to distribute a point load on the outside.

If you model it like a paddling helmet, with suspension, that will probably work for drifting along in a river at a jogging speed and bumping into rocks, but I don't think any of those paddling helmets would pass a "real" helmet impact test like what is done for ski helmets, bike helmets or motorsports helmets.

I'd like to make a cool helmet too, so if you figure out the inner foam thing, let me know.

Peter


Last edited by foam-n-fibre on Fri Sep 27, 2013 12:55 am, edited 1 time in total.

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 Post subject: Re: Helmet build
PostPosted: Thu Sep 26, 2013 11:00 pm 
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Location: Chile/Brasil
here is an idea :
grab a decent bike helmet and cover it with kevlar inside shell and outside shell.
i guess most army and marine helmets are made from balistic kevlar not carbón.
cheers! :thumb:


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 Post subject: Re: Helmet build
PostPosted: Fri Sep 27, 2013 3:13 am 
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Thanks guys for your comments.

It is just an idea atm, duno if it will work. I do not like heavy helmets but I see a need from sharp objects.
There is no universal solution and Gath helmets are not to bad. Do they have any foam inside? I'm not too sure.

Now I'm thinking to use a closed cell foam 5mm, maybe cut in strips, glued and shaped inside.


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 Post subject: Re: Helmet build
PostPosted: Fri Sep 27, 2013 5:52 pm 
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Location: Southwestern Ontario
Gath helmets do have foam on the inside, Its like a formed styrofoam and the provide weather striping to add a custom fit


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 Post subject: Re: Helmet build
PostPosted: Sat Sep 28, 2013 8:30 am 
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Location: Iv.G.-Slovenia
I don't know what is a heavy helmet for you.
I bought a ProTec Twoface helmet. It weights 525 g. On the other hand Hero2 weights 225 g (with water proof housing).
I don't think all the work is worth for the bad results you can get.


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