Carbon helmet layers

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drking
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Carbon helmet layers

Post by drking » Thu Feb 18, 2010 8:12 am

Hi,

Does anyone know approximately how many layers of carbon go into a helmet such as the early Strutters or a happy2b? I have had quick google but can't seem to find anything.

Cheers,

Dan.

guy
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Re: Carbon helmet layers

Post by guy » Thu Feb 18, 2010 9:40 am

You also need to know how thick the layers are, and if they were laid up by hand or were vacuum molded.
Assuming you are thinking of making one yourself :-)

I'll measure my NFA later and let you know how thick it is.

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drking
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Re: Carbon helmet layers

Post by drking » Thu Feb 18, 2010 10:20 am

Hi Guy,

I'm laying up by hand and using a 2x2 twill Carbon. Not sure of the thickness but its pretty thin and delicate compared to the glass woven roving i practiced with. Thinking from a safety point of view I was going to go for two carbon, one kevlar and another two carbon layers. The kevlar I have is easily twice as heavy/thick than the carbon twill I have.

I'm just pretty intersted to see what the pro helmet makers were going for.

Cheers,

Dan.

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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Thu Feb 18, 2010 6:18 pm

Sometime manufacturers just have a layer of carbon fibre for show, then the rest is built up with diolen/ twill weave etc. A clear gel coat will protect the delicate carbon fabric. I have a feeling its usually about 8 layers of fabric that goes into a helmet

Have you made a female mould? If so how does the fabric drape into the shape? Sweet Strutters are made using heat and high pressure to get the shape out of one piece with no cuts in the fabric. With hand lay ups getting the fabric to drape can be difficult.

I have spent many a hour working on helmet designs and lay-ups and its often disappointing and costly. My main bit of advice would be to be happy, really happy with a shape then do a test with paper mache, this way it doesn't cost as much.

Hope any of the above is helpful.

Jonny

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drking
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Re: Carbon helmet layers

Post by drking » Fri Feb 19, 2010 7:25 am

Hi Jonny,

I took a Shred Ready helmet and riveted a baseball cap to the front so it was a Strutter style shape. Then from that made the plug and then mould. I have layed up a couple of glass helmets with polyester resin and coloured gel coat just to practice and then yesterday I did a carbon/epoxy one. The 2x2 twill lays really well in the mould. No need for cutting etc. Although very delicate it seems much easier to work with and the finish is instantly better. I will release it sometime over the weekend hopefully. Some photos from my phone are here http://s217.photobucket.com/albums/cc13 ... ng/helmet/

Have you looked into straps and padding etc for your projects?

Cheers,

Dan.

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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Fri Feb 19, 2010 9:14 am

Check out ace supplies 4 webbing and buckles, l havnt found anywhere that does foam yet, the stuff fna uses would be ideal. Did you use wax releasing agent on your mould? Jb

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drking
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Re: Carbon helmet layers

Post by drking » Fri Feb 19, 2010 4:10 pm

Yes. I used Meguiars Mirror Glaze 16 which I picked up from a performance car shop. Works a treat. Its an awful feeling not knowing if the helmet is going to release or not isn't it. With this stuff I just trim the fabric back until its nearly flush with the mould and give the mould a couple of whacks with a rubber mallet and so far it has just popped out. Nice.
Got any photos of your lids? Thanks for the ace supplies tip.

Dan.

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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Fri Feb 19, 2010 5:24 pm

Ill have to try that mirror glaze stuff, Ive just been using wax and it sticks sometimes. Altough the shape of my helmet is more for creeking and is harder to mould.

Ill get some pics up online soon, is it a 2x2 twill weave that you use for the glass fabric aswell?

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drking
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Re: Carbon helmet layers

Post by drking » Fri Feb 19, 2010 5:37 pm

I used glass woven rovings for the two practice ones. It wouldn't drape at all so inside the helmet looks untidy with random cuts in the fabric to make sure the mould was covered. Getting the gelcoat right is proving to be tricky aswell. The twill is the way to go. I think you can get a biaxal (sp?) cloth which is stitched together so will drape well. These are my first few attempts so its real trial and error.
Did you make a plug and female mould? What did you make your plug out of if you did?

This is what I use: http://www.performancemotorcare.com/aca ... _312g.html

Dan.

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Re: Carbon helmet layers

Post by BigMike » Fri Feb 19, 2010 6:21 pm

If you use twill then you could have a look at vacuum bagging the mould then you wouldn't have the gelcoat issues. Also, if you use epoxy and do a fairly thin layer in place of the gelcoat, wait til it gets fairly tacky then start your layup, you might get a stronger, more even (in resin terms) result. I've tried this with helmets in the past and found that the resin was not thixotropic enough to retain the even layer, it always ran and caused problems. These days you can get resin which is really thixotropic but you have to make sure you stir it really really well as the (cant remember the name of the stuff that thickens it) *stuff* ends up at the bottom of the tin so its crucial you stir it for ages.

you might find the carbonmods.co.uk website interesting - they sell bagging supplies as well, and I'm sure you could rent the hardware if you fancied giving it a go.

I've been thinking about having another go at this, principally because I can't find a helmet to fit me, and my old Ace is ready for the bin, but right now I can't find a helmet to even start to make the beginnings of my plug from. A SR full mental jacket would be ideal, but I just can't find one anywhere.

BTW, if you're using epoxy you should wear a respirator. I'm sure you know this anyway but just thought I'd mention it, it's evil stuff.

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Fri Feb 19, 2010 7:54 pm

Composite reinforcement materials go by grams/sq mtr not thickness . At a guess 3 layers of about 400 gr carbon biaxial cloth would produce a strong item if well worked with good epoxy. You can at extra patch reinforcement at critical areas ie strap bases. A vaccum will almost double the strength/ weight ratio. Some kevlar is good for impact resistance as all carbon although really strong can be brittle. Wessex resins is a good source and their reps are usually very free with good advice, They taught me enough to build a 38 foot trimaran
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guy
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Re: Carbon helmet layers

Post by guy » Fri Feb 19, 2010 8:38 pm

Sorry for the delay getting back to you.
My FNA http://www.2at.com/fna/index.htm
is an x-stream and is just over 3mm thick
the chin guard is a bit thicker at nearly 5mm (but that is probably down to poor quality application of the gel coat)
It does have a gel coat because it has glitter :-)
and it weighs 730grams including padding + strap
inside I can see what looks like a carbon+kevlar weave
out side it is is a bi-axial weave - I don't know what material could be fiberglass or diolen
both fabrics look like 150 gram fabrics

A Strutter is 500g

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Re: Carbon helmet layers

Post by guy » Fri Feb 19, 2010 8:58 pm

Don't forget if you use 2 layers of woven cloth you should use some chopped strand mat in between if you are using polyester resin.
If you use epoxy then the csm is not required - because the epoxy has a better bond.

Epoxy has a better life expectancy too - polyester will have degraded quite badly in 10years
but I'm sure fashion will have changed by then and you will be making the next model.

Which reminds me - anyone want to buy a 20 year old fiberglass WW2 German style helmet
Not dissimilar to this oneImage
but in blue with pink and purple streaks.

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drking
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Re: Carbon helmet layers

Post by drking » Sat Feb 20, 2010 9:57 am

Firstly, thanks for all the advice and information folks. I just checked and the carbon I have used on the first one is 200g. So I have two thin layers of clear gel coat, two layers of 200g carbon, one layer of Kevlar (400g i think) and one more layer of 200g carbon. I have used West Systems Epoxy. I'm going to release this one as it is just to see what it is like and I've run out of carbon at the moment.
Vacuum Bagging sounds like a good way to go but at the moment its abit of a shed style project just to see if its possible or not.
Whats a recommended time for the helmet to be in the mould? I have been releasing it after about 24hrs but can I leave it longer?

If it works out ok I quite fancy doing something like the FNA Xtra next.

Thanks again guys,

Dan.

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sat Feb 20, 2010 1:22 pm

You can leave it in mould as long as you want. Higher temp will speed cure. Bye the way, if youve never used epoxy, extreme accuracy is needed to measure the resin and hardener. Use syringes for small batches or a 0.5 gram accuracy digital kitchen scale for larger batch. Some people seem to think you can add more hardener for a quicker cure ,but if you do the mix will never harden but will remain rubbery. West system from Wessex resins is good as is SP systems or MAS epoxy. Another great supplier is Matrix Mouldings in Bristol. They will sell small quantities of carbon or any fabric so you wont have to buy the whole roll. The boss (a chap named Wiz) is extremely knowledgeable and will teach you what you need to know. They sell a great resin by French manufacturer Sicomin.
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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Sat Feb 20, 2010 3:00 pm

What a great post, Id all but given up on helmet making and lost interest but im back in the garage sanding away again. The problem I have is getting the right shape, ive been starting from scratch and its hard to get it symetrical, fit your head and not look like a plant pot.

This video was done about 5 years ago,

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sat Feb 20, 2010 4:02 pm

Gell coats are not normally used in high performance composites as they do not contribute to strength and add weight. Instead, the item is given a finish after its been made (2 pack paint or clear laquer) applied by spray gun. Gell coats are a throw back from the days of polyester resin and chopped strand mat and are a very poor relation to what youre talking here
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BigMike
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Re: Carbon helmet layers

Post by BigMike » Sat Feb 20, 2010 6:06 pm

Dan, don't use a gel coat layer if you're using epoxy, there's no need. See my other post above. as swamp says, its not used in epoxy layups and can crack and split if you use it. you just need to make sure you "paint" the mould with resin which is thixotropic enough to retain the coating, then when its tacky, do your layup.

Also, if you're using west sytems, make absolutely sure that you have laminating resin - sorry if this is granny/eggs scenario, but its important so worthy of mention I think.

In terms of mould release, you can leave it as long as you like really, but as an absolute minimum I'd leave it 48 hours - if you're doing it in a shed and the shed isnt heated, I'd leave it a week, in fact probably longer. HTH.

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drking
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Re: Carbon helmet layers

Post by drking » Sun Feb 21, 2010 3:24 pm

Thanks again guys. Mike, don't worry about the sucking eggs scenario, all information is good. I haven't worked with composites much at all so there is lots to learn and its easy to forget important stuff. I think I wil release this one, check it out and maybe drop a few rocks on it like in Jonnys video!

I'm using laminating resin so thats cool and i'm lucky enough to so far nab a small corner of a workshop at work thats constantly heated to around 23*C so thats nice.

If i'm not putting a gel coat on it, can I add pigment to the epoxy for the top layer?

Swamp - thanks for the Matrix Mouldings tip. Had a look at their new website - Matrix Composite Materials Company and going to give them a call about some fabric.

Its great to have a resource like this (ukrgb) I've learnt alot in the last few days.

Cheers,

Dan.

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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Sun Feb 21, 2010 3:40 pm

Does anybody know where to get some helmet foam from? The strips from FNA seem the best as they are self adhesive on one side. Shred Ready use one piece cut to fit the helmet, anybody know what the brand name is?

Jonny

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sun Feb 21, 2010 7:16 pm

Pigmented resin will only give a satisfactory finish in a high viscosity format ie gel coat, applied in a thick layer. Not really what you want for your job. Your far better painting it after cure, with the bonus of custom artwork being a reality
Lost your job? Wife ran off with your best mate? Bailiffs coming for the Audi? Thinking of topping yourself? Dont call the Samaritans, come for a paddle.
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Re: Carbon helmet layers

Post by Swampthing » Sun Feb 21, 2010 7:22 pm

Johnny. cut some foam from a camping under mat and contact adhesive in place. Its about 12mm thick and waterproof
Lost your job? Wife ran off with your best mate? Bailiffs coming for the Audi? Thinking of topping yourself? Dont call the Samaritans, come for a paddle.
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Rinseout
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Re: Carbon helmet layers

Post by Rinseout » Sun Feb 21, 2010 7:25 pm

Swampthing wrote: Your far better painting it after cure, with the bonus of custom artwork being a reality

Im thinking of painting some graphics on my helmet (SR Sherlock) and was wondering what paint should i use for a nice glossy effect or just normal paint with a coat of lacquer?

George

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sun Feb 21, 2010 7:31 pm

If you have a comercially made lid its not epoxy but an inferior plastic and wont like paint
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Jonny Briggs
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Re: Carbon helmet layers

Post by Jonny Briggs » Sun Feb 21, 2010 7:34 pm

Yes I have used camping mat foam before, I think the technical name is cross linked PE foam. Just done abit of research, there are quite a few extruders that do it in the UK. I think FNA just gets the foam in a block at the desired thickness, rips it down to right width then sticks double sided tape on.

JB

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Rinseout
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Re: Carbon helmet layers

Post by Rinseout » Sun Feb 21, 2010 7:43 pm

It's not plastic though (Shredlar Armid fiber /fiberglass composite) lid with a red paint on it already

http://playak.com/article.php?sid=1077

George

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drking
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Re: Carbon helmet layers

Post by drking » Sun Feb 21, 2010 7:48 pm

Jonny, I have emailed these guys today for some information. They have helmet liners in their products page for military and sports and leisure etc. http://www.kewell-converters.co.uk

Swamp, On top of the Epoxy I can just get my panel sprayer mate to paint and lacquer the lid then?

Cheers,

Dan.

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sun Feb 21, 2010 7:54 pm

Yes. Spot fill any imperfections then a rub then hi build 2 pack primer then 2 pack paint
Lost your job? Wife ran off with your best mate? Bailiffs coming for the Audi? Thinking of topping yourself? Dont call the Samaritans, come for a paddle.
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Re: Carbon helmet layers

Post by BigMike » Sun Feb 21, 2010 7:57 pm

or maybe just have your outer layer as carbon then you'll get that fantastic carbon look as it catches the light

if you're dead set on colour, then maybe a vinylester resin would be better, not as strong as epoxy though.

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Swampthing
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Re: Carbon helmet layers

Post by Swampthing » Sun Feb 21, 2010 8:03 pm

Rinseout. Im not familiar with that make but if as you say it is allready painted then it should be ok. 2 pack paints are always top of the heap. Check with the manufacturer first, some paints will deteriorate some plastics over time
Lost your job? Wife ran off with your best mate? Bailiffs coming for the Audi? Thinking of topping yourself? Dont call the Samaritans, come for a paddle.
3 cheers for rap music.........Hip hop.................

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