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


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8 hours ago, flyingbrick said:

Damn that's a great idea (composite overflow) I need a weird shape one for the bike, why didn't I think of that ffs. 

I wouldn't bother with that plastic but that's just me.  Foam works great, easy to shape and you can dissolve it out later on. Plus it's cheap and accessible

I would probably cover the area that I want the bottle to now occupy and fill it with packing tape etc then use foam to rough out a template.

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Temps will be way high for west system, will need to pick the resin carefully.

The tank would be simple and straight forward to make, variety of methods to achieve the end goal, pick the one you like the best.

Biggest single hassle is the inlet/outlets, getting fibre orientations etc so they don't snap off or enlarging the bond area to handle it can really complicate things.

Perhaps a bond in flange for the cap with integrated fittings?

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1 hour ago, NickJ said:

Temps will be way high for west system, will need to pick the resin carefully.

The tank would be simple and straight forward to make, variety of methods to achieve the end goal, pick the one you like the best.

Biggest single hassle is the inlet/outlets, getting fibre orientations etc so they don't snap off or enlarging the bond area to handle it can really complicate things.

Perhaps a bond in flange for the cap with integrated fittings?

Why would temps be high? Isn't it rated for 300deg c? 

Inlets and outlets easy,  could simply lay up a thicker pad of material and drill /tap for screw in nipples. 

 

 

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1 hour ago, flyingbrick said:

Why would temps be high? Isn't it rated for 300deg c? 

Inlets and outlets easy,  could simply lay up a thicker pad of material and drill /tap for screw in nipples. 

 

 

Unfortunately not, West is 40-50C then it really gets soft, with post cure you can push it nearer to 70C but even then I wouldn't want to go over 50 service. Of course this will be fine if there are no structural loads (Pressure) it may just deform over time or leak a bit.

Adr 243 + 140 hardener will get you in the mid hundreds happily, may even get away with a service post cure depending on layup technique.

Potentially get away with tapered fittings but it will be prone to small leaks through thermal cycling, BUT I design these things for vacuum service so my expectation for leak tight might be a bit excessive!

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Cheers, sometimes posts in here are on another level and I have to go away and do some googling lol.

Alright, ADR 243 + 140 hardener, what's the best place to get fiberglassing stuff from? I have seen nzfiberglass.co.nz but had to go to https://www.adhesivetechnologies.co.nz/Products/Laminating,-infusion-and-pre-preg-resins/ADR246/ for info on ADR resins etc 

I could always just get an aluminium drink bottle/container etc of the right volume, or 'flip' the oem overflow to the other side of the car, but my window washer bottle is fugly and takes up a lot of unneccessary space (plus lots of air beneath it) and I could make things a bit more streamlined. 

Also what stuff is good for dissolving foam? 

~ Plus a dumb question haha - why do moulds made for making lots of parts go bad after x amount of parts have been made from it? I've just seen a business on the tard have quite a bit of negative feedback from customers saying their bumpers etc they ordered are out by 10-20mm in places and panel shops not wanting to touch them due to parts being thin/too shitty. 

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Some of the resin used can shrink over time, but also some moulds especially for bumpers etc are made from a copy of a copy of a copy of a copy of an original part.
So you get a big dimensional "creep" if every copy is say 1mm out from the original haha.

Many moons ago a friend bought a replica TRD widebody SW20 kit for "cheap" 

Which was fucking abysmal, like dimensionally wrong to unusable levels on every part. It was like it was made for a 3/4 scale car.

He then spent a fortune persisting with it, and ended up with it still looking like shit. 
Then sold the car as an unfinished project for pittance.

Also, sometimes moulds can just simply not deal with the mechanical forces from separating the part.
Like sometimes people are needing to hammer in wedges around the edges to split it.

You can make moulds strong enough to be massively more reusable, but it's a tradeoff of how many parts you're actually wanting to make. 
If it's just a one off you're probably not going to spend a zillion hours and lots of materials making an infinity strong mould.

 

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The former owners of the ex-Summerfield VRS practically left a jizz stain when they saw the wife's one sporting 99% of a genuine WRC kit and were fizzing at the prospect of taking moulds until they realized out the amount of work involved and the number of replacement parts they'd need for a season. 

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  • 2 weeks later...

Today I downloaded fusion 360 with the 1 year free trial and for fun tried to create a sketch of my front bumper with the end goal of seeing if I could model a lip/extensions different shapes etc. 

Not much luck, I'll have to keep playing round with it and watch more YouTube!

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I recently bought this vacuum formed hull off trademe. It's quite a nice wee hull but is fairly flimsy as it's only plastic. I want to make a copy of it in fibreglass so it's a bit tougher. How would you guys recommend I go about making a mould? I've been reading up on it but keen to hear some real world advice as there's an overwhelming number of options.

hnNemrC.jpg

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It's part of a vintage kit so I don't want to destroy the original hull in the process. It would also be a bonus if more than one hull could be made but it's not essential. I've removed the motor mount, rudder post etc and will patch the holes up. 

At this stage I'm thinking the way to go will be to clean up the inside of the hull, apply some sort of release agent and then fill it with plaster of paris/liquid latex etc to form a plug. Then fibreglass over this plug to make a hull. 

Does this seem plausible to you guys? And if so, what would you recommend I use to form the plug? Thinking I'll just use a fibreglass kit from Bunnings for starters as it seems a pretty cheap/easy way to purchase everything I need to start out.

 

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On 09/08/2021 at 14:18, chasinthemirage said:

I recently bought this vacuum formed hull off trademe. It's quite a nice wee hull but is fairly flimsy as it's only plastic. I want to make a copy of it in fibreglass so it's a bit tougher. How would you guys recommend I go about making a mould? I've been reading up on it but keen to hear some real world advice as there's an overwhelming number of options.

hnNemrC.jpg

31wwcZi.jpg

eEbwSXu.jpg

It's part of a vintage kit so I don't want to destroy the original hull in the process. It would also be a bonus if more than one hull could be made but it's not essential. I've removed the motor mount, rudder post etc and will patch the holes up. 

At this stage I'm thinking the way to go will be to clean up the inside of the hull, apply some sort of release agent and then fill it with plaster of paris/liquid latex etc to form a plug. Then fibreglass over this plug to make a hull. 

Does this seem plausible to you guys? And if so, what would you recommend I use to form the plug? Thinking I'll just use a fibreglass kit from Bunnings for starters as it seems a pretty cheap/easy way to purchase everything I need to start out.

 

Hey man. 

No, don't use a plug to make your new hulls. You will end up with a nice Hull interior and a shit exterior which requires untold hours of filling and sanding. 

You need to make a normal mold of the exterior of the Hull. In practice, once you knuckle down and do it this won't take long. 

I'd start by turning the Hull upside down and gluing it to a flexible sheet of something like coreflute. You could slice one side of the material along it's grain so that it flexes easily in one direction but is still rigid in the other. Put the uncut side toward the hull, push it into a curve of the hull (where the deck would usually fit) and glue it firmly to the hull with hot glue so that the mold is formed with a sturdy perimeter lip. 

Then seal any gaps or holes with quality modeling clay, smash down some wax and then lay your fibreglass.

Start with straight resin mixed with pigment to make a gel coat (so you can see where it's going), wait for it to firm up until just tacky then add fibreglass tissue, then cloth or mat. 

 

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Nah when it cures normally in a thin layer with fibreglass etc, it cant generate enough heat to get into the run away cycle of blowing itself to smithereens. 

The cure time of epoxy on a part is way way higher than when your pot of epoxy will go off. 

This time of year when it's cool you might not have too much trouble with either, anyway.
 

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