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Almost there, helmet cont.

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downunder
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Almost there, helmet cont.

Postby downunder » Thu Dec 19, 2013 1:27 pm

Hey guys

I'm quite excited :) Hence opening a new thread with a final product!

At this stage it is a prototype. But, a promising one!

First, some triax 700g/m^2 cut into this shape. It is extremely important to cut it for your mold.

DSC00577 (Small).JPG


See this gaps? Orange color is a rubber swimming hat. Will keep it for a better seal.

After positioning I am after no gap at all and a second cut will fix this.

DSC00575 (Small).JPG


Than goes carbon kevlar wrap (sorry no photos, stressed out 100%).

Vac this baby! Using ziplock bag and one way valve. Keeping vac for hours!

DSC00579 (Small).JPG


DSC00578 (Small).JPG


I'm always exited after taking it off a vac bag!

Cutting off the mold! Yes, cutting with carbide bit is not for a faint hearted:

DSC04611 (Small).JPG
DSC04611 (Small).JPG (124.68 KiB) Viewed 1851 times


Happy days! 183g !!!! Not finished yet, and there is a space for some weight reduction (KC only?)

DSC00587 (Small).JPG


Nice hey?

DSC00583 (Small).JPG


Curved back side reinforcement:

DSC00584 (Small).JPG


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!

Btw, it is hard as a rock! It can't even be compared with a Gath (sorry Gath!). I recon there is no way to smash it with a hammer, but if I'm super keen will destroy one for sure:)

Already planning a next one! Same KC + FG but one layer only. This has got two. The mold is fine, can be reused number of times. Just some more plaster to fix the cuts after demolding.

My ultimate goal is less than 200g!

Hope you like it!

D.

PS

Cost? About Au$35.

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Re: Almost there, helmet cont.

Postby Toby » Thu Dec 19, 2013 7:41 pm

looks fantastic!

Did you do some stripes into it, so it becomes more reinforced? (like channels)

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Re: Almost there, helmet cont.

Postby downunder » Fri Dec 20, 2013 1:40 am

Thx Toby, very much appreciated!

Yes, channels indeed!

Cheers
D.

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Re: Almost there, helmet cont.

Postby plummet » Fri Dec 20, 2013 5:18 am

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?

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Re: Almost there, helmet cont.

Postby downunder » Fri Dec 20, 2013 5:43 am

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!

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Re: Almost there, helmet cont.

Postby plummet » Fri Dec 20, 2013 6:23 am

rubber lining? Like a door strip?
Bend the foam around the edge?

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Re: Almost there, helmet cont.

Postby plummet » Fri Dec 20, 2013 6:24 am

yes female mould will do it. Harder to vac bag though.

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Re: Almost there, helmet cont.

Postby downunder » Tue Jan 21, 2014 8:00 am

At the end, the helmet is a bit tight on a sides for me. Duno why, maybe I sanded a mold too much.

Not a big deal. Can slap some plaster and adjust the mold.
It was a huge learning curve. So happy with a result even tho not perfect (is anything?):

So, now to make it a bigger, use maybe 1 layer 3-axle FG and CF. Might use FG only for testing tho.

Will see...

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Re: Almost there, helmet cont.

Postby plummet » Wed Jan 22, 2014 8:17 am

picture update?

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Re: Almost there, helmet cont.

Postby dragnfly » Wed Jan 22, 2014 10:01 am

Wouldnt you want some padding in there??


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