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Fibreglass, Carbon Fibre, Paper Mache - The composites chat thread

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Carbon fiber does conduct electricity. It is not as good of a conductor as most metals, but if you build a structure with it, you will find that its electrical conduction can easily contribute to galvanic corrosion, by electrically connecting dissimilar metals.

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So what's the plan there? Make them all up then slice the sides to fit them together, then enclosure or open? 

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Yeah make a jig so i can trim each side accurately. 

Will be enclosed in an airbox eventually.

Gonna make a flowbench so i can test a few different schemes.

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That looks amazing man.. super professional. Big units too! Could sell them to honda guys for putting into their bumpers for cold air lol

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The bellmouth I made previously for a 3" inlet pipe with same geometry is bloody huge hahaha.

Cant wait to get flowbench setup and do some nerding with it.

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This thread has inspired me to dip my toe into the world of composites.. (please don't use any of the below as advise just observations from a noob)

 

First attempt on a headlight mould to make more headlightly type things for my pos racecar.. no idea if I'm doing it right.. or if it will release properly..

if it does the next step will be to use the mould to produce a headlight blank. If it doesn't I'll need to figure out why and try again. .

Made an edge barrier out of junk, cleaned sanded, cleaned etc..

 

Laid down 7 coats of wax -/ mould release.

2 coats of PVA.

1 coat of moulding Gel coat, next time I will use a bit less than 2% catalyst as even on a small thing like this I ended up in a hurry.

2 layers of 200g cloth.

2 layers of 225 chopped strand

1 layer 450g chopped strand.

(No idea if that will be strong enough)

What I noted is that working the cloth required scissors to get it to shape nicely whereas the chopped strand behaved better when pulled apart..

When the mat wasn't behaving more resin seemed to help. 

The little roller thing I purchased isn't much good dabbing with a brush was the successful method.

Be prepared to go through a fair few brushes and mixing cups etc and set up a covered area on your workbench. And use disposable gloves etc...

It's hard to tell if you are pushing the first layer of mat through the gel coat- I reckon the inside may have signs of this if I get to split the part open.

If it turns to shit I will delete this post and deny having done any fibreglass work..

20181130_112140.jpg

20181130_145640.jpg

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Awesome look forward to seeing results! 
Inspiring me to do some more stuff too have been lazy.
Man one of the best things I've bought is a super sharp set of sewing scissors.
Good snips makes a huge difference.



 

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Yeah i find not a nice finish with pva. 

Well its ok but not shiny straight out of mould like you might get from super polished + wax. But thats risky.

Awesome result!

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I have seen people getting a good finish with PVA. Unsure if they are maybe thinning it somehow before spraying? I find it always dries to a satin finish no matter what I try.

You cant wax too much.

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22 hours ago, sentra said:

Pva belongs in the rubbish bin 

Please tell me there is something in a spray can I should be using instead of PVA.

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There are spray on waxes and release agents. I saw one on the shelf at the fiberglass shop in hamilton. Pretty sure they are wax.

 

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Had to fight for over an hour to get the  second light out of the l/h mould. I was willing to sacrifice my $20 light to save  the mould. Below is the remains of the light.

20181207_191048.jpg

Also my aliexpress carbor fibre turned up today, man you have to be careful not to open up the weave!

Will find out if I have managed to make a thing or if I have wasted a bunch of time and have zero to show for it.

this is just 2 layers of cf and budget polyester resin. It went off a bit too quick for my liking probably because it was pretty hot in my shed this afternoon.. I'm pretty confident it won't be great on the finished side but may be salvageable.

 

20181207_185221.jpg

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Certainly not perfect, a couple of bubbles on the surface, and spots at the edge where the resin didn't fill right out,  but the weave underneath looks better than I anticipated.

20181208_095358.jpg

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That is extremely impressive. Just drip some resin into those voids, sand smooth then give the whole lot a coat in straight resin. If its anything like my epoxy it will level out and go crystal clear and smooth as glass

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Hey dudes, I've had a read through this thread but am still a bit unclear on the best way for me to go about what I am trying to do. I'm in the process of shaping a comb raiser for the stock of my rifle to bring my line of sight up to where the new optic is mounted. I am currently using high density foam to shape a template, once this is finished what would you guys recommend as the next step? Do I need to go to the trouble of making a female mold from the template and then fibreglassing this or will a couple of coats of reinforced filler/bog over the foam be sufficient? It needs to be fairly sturdy as at some point its likely to get dropped but weight isn't too much of an issue and neither is the ability to make another as this is likely to be the only rifle of this type I build for awhile. 

 

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Sanded and polished,  finish is a little better but not amazing, the voids are flat now but did leave a visible bubble under the surface for some reason.

I think could in part be the difference between cheap polyester resin which is not doing a great job of self levelling when compared to proper epoxy, and leaves a slightly dull finish.

Did at least get rid of the pva streaks. Went from 600 wet sanding to polish because I didn't have any 1200.

If it turns to crap down the track I will spray on some 2 pot clear.

 

20181209_082126.jpg

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22 hours ago, chasinthemirage said:

Hey dudes, I've had a read through this thread but am still a bit unclear on the best way for me to go about what I am trying to do. I'm in the process of shaping a comb raiser for the stock of my rifle to bring my line of sight up to where the new optic is mounted. I am currently using high density foam to shape a template, once this is finished what would you guys recommend as the next step? Do I need to go to the trouble of making a female mold from the template and then fibreglassing this or will a couple of coats of reinforced filler/bog over the foam be sufficient? It needs to be fairly sturdy as at some point its likely to get dropped but weight isn't too much of an issue and neither is the ability to make another as this is likely to be the only rifle of this type I build for awhile. 

 

I know a guy that makes very cheap adjustable cheek rests. I have one here i could get photos of if ya want.

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