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

[NickJ]

Just select the resin on what you're doin (generally you'll have to post cure above the expected service temp) but resins do exist that can handle much higher temps.

If you want to give prepreg a go, the silicon may be too soft, don't want to say it won't work, but chances are once the vacuum is on it will distort, dunno how much of an issue this will be? Also try printing the insides of the manifold and wrap the carbon around the outside, laying up prepreg on internal surfaces + vacuum is a pig.

[flyingbrick]

Evan could you make inner/outer molds from silicone and pour in a fiber reinforced epoxy resin? Like newtech but runnier.

[Evan]

I've considered that, could make some additional moulds to work with what I've got and give that a go too, I just don't know if it would be runny enough to get into all the spots.

[flyingbrick]

On 4/26/2018 at 18:16, mjrstar said:

I have an old EK civic hillclimb machine, nothing too flash. It's probably more for the skill and experience than the outcome.. ideally I do want to trim a few more kg's out of various bits and pieces after coming to grips with the process...

 

 

If you havent seen it already (unsure if its been shared on here) there is a guy on youtube building a CF 240z.. his panels are all made without molds and this is a good option for guards etc.

If you want someone else to do those light covers let me know. Would happily do it for $100 to cover materials etc.

Alternatively, if you havent started before i've built my new shed- pop over for a few beers and ill do it with ya over a few afternoons. 

 

[Evan]

I've watched a few of those vids of that CF 240z. It's a bit of a balls up how all he is doing is laying carbon over the factory panel to make the new panel, then removing the original panel to attach the new CF panel. The whole car is going to end up fractionally larger that it should be, curious to see how it affects panel gaps and things like tail light fitment. Also the nice smooth finish ends up being on the inside of the panel, which you don't see...

[tortron]

#wdebdy

[flyingbrick]

59 minutes ago, Evan said:

I've watched a few of those vids of that CF 240z. It's a bit of a balls up how all he is doing is laying carbon over the factory panel to make the new panel, then removing the original panel to attach the new CF panel. The whole car is going to end up fractionally larger that it should be, curious to see how it affects panel gaps and things like tail light fitment. Also the nice smooth finish ends up being on the inside of the panel, which you don't see...

All very true evan BUT when laying cloth down like he does you end up with a relatively smooth surface that only needs a quick sand and flow coat of resin to reach 99%

Quality resin self levels extremely well (eg on surfboards and did i post pictures of my scooter tank?)

I think the extra mm or so of panel thickness will not be noticeable- worse is done every day AND the difference is probably that its hugely less labour and materials intensive.

[flyingbrick]

My intake mold is going to be 3 pieces due to a lack of draft angle behind the throttle. If it was to be made in one piece then it would end up trapped for good. 

I had been making walls/dams using children's modeling clay (fuck my life, lets not go there) but this time used self adhesive foam seal- soaked in wax and PVA glue- it worked extremely well.

One more section of mold to go! hopefully my CF wont take too long to arrive from AE and then i can put this little project to rest.

Note the main mold flanges have little nipples there for the two smaller sections to locate into.

 

[CorollaGT]

What are people using for epoxy to bond fibreglass and alloy?

I have a spoiler that has no mounting hardware to allow it to be bolted to my boot. Thought is to glue an alloy plate with a some rivnuts underneath the spoiler to give a solid base to bolt to the boot. Not keen on using self tappers like what was done previously by the looks of it.

[kyteler]

Panelbond should work.

https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Panel-Bonding-Adhesive/?N=5002385+3293241847&rt=rud

[Roman]

Haha this cracked me up

http://www.motoiq.com/MagazineArticles/ID/1704/PageID/2400/Project-Miatabusa-Part-43--The-Intake-Manifold.aspx

[Roman]

Also my latest CF related abomination

I thought it would be an interesting idea to try make some molds for a destructable inner core that I could easily make a bunch of. 
So firstly drew up a trumpet shape that I wanted to make (omitted the return curves for simplicity for starters) 



Then made a 2 piece mold following the inner surface shape and added some locating tabs 



3d printed it like so and filled it up with plaster



It took a few goes to figure out how to avoid bubbles in the finish and blah blah, but got a nice result eventually. 

So the great thing about the plaster is that just a quick whisk of sand paper and you've gotten rid of any layer lines from the 3d printing. Get a super smooth finish which is awesome. 
But the big problem is that its massively porous. 
So I thought giving it a coat of epoxy would give it a nice glossy finish that the final part would seperate nicely from.

So did that, left it for a day and it ended up with a really nice glossy finish. 

So PVA'd over this (No wax which was a mistake. mistakes were made. I'm stupid. etc)

Then bunged some CF sleeve over the top and some normal matting at the bottom to cover over where it's thin. 



Then vacuum bagged this, with wet layup.
Had some problems with the bag not being able to tighten fully up to the part, as I didnt allow enough bag size essentially.
So I had to fiddle with a it a bit which ruined the outer finish and creased part of it. Bums. 



Annnnddd then my second problem. 
Coating the plaster with epoxy to seal it creates this rediculously hard outer layer that is almost impossible to smash haha. Damnit.



Underneath the parts I've managed to break/pick off, it's got a super nice finish where it was up against the glossy epoxy finish on the plaster.
The PVA seems to be doing its job to some extent as when you pick some of it off there's a clean seperation. But it just seems mechnically locked in place since theres still a curve all of the way around sticking to the part, and both the part and the plaster are stupidly rigid.

But I'm really happy with what the internal finish looks like where it was up against the mold. 
I dont have the patience to get this entire part unstuck, and there's no point because the outer of it looks yuck anyway. 
So I'll try find a better way of making that center core part and try again.
I've ordered some PVA filament which is dissolvable, so I could 3d print a core that just washes out after. But it takes ages to print, need to sand the layer lines every time, and is expensive. So if I can make plaster or something similar work (any ideas for another something similar to use?) I'll stick with that. 
But if the plaster needs epoxy or similar every time, PVA might just be more cost effective as well as a lot less messy. (It's stupidly good fun pouring plaster and then seeing something cool come out of a mold though)

I think my next iteration of this piece will be good.
My resin infusion is working awesomely now so I'll do that again for the next iteration.
It's much easier to sort out any of the bagging issues when the bag doesnt stick to the part because it's already wet with epoxy. 

TL;DR: Lots of time and materials, have produced nothing useful since previous posts, still have hope for non shit parts in future

[flyingbrick]

very cool mate. Had a real laugh at your pics.

Candle wax mold? or how about you use your mold to cast a silicone dildo plug thing. 

And yeap.. must always wax AND pva. I've been astounded at how I can wax it 5 times then pva and STILL have little bits stick. 

[Roman]

I think pva glue might be the answer for sealing the mold. Its water soluble, fairly thick so doesnt massively soak in, doesn't strengthen the plaster too much, super smooth finish, non toxic and cheaaap. And can wax / pva release agent over the top too.

Will give it a go.

[Roman]

Success!

 

Edges need trimming but you get the idea.

Pva glue over plaster was the good combo. Then a little wax for good measure.

Carbon sleeve is the best!

The inside is super smooth and tgecoutside feels like crocodile skin or something. The biaxial weave is really cool.

Gonna order a bunch of different sizes I think.

This one is probably a tad flimsy with only one layer of sleeve but two will be sweet with a 6k weave I think. Or maybe just go 12k single.

But it's probably lighter than the bolts that would hold it in place.

Only about 25 more prototypes and I'll have a usable part haha

[flyingbrick]

For the past few weeks i have been working sporadically on a carbon fiber dashboard for the HQ. My first time working with CF at home and it has some interesting quirks. 

The project is driven by that amazing CF datsun on youtube- most panels are made using a plug rather than a mold (eg, inside out compared to what youd usually do)

Aside from sharing photos id like to bring everybodies attention to AMINE BLOOM as its something that i had not struck during previous projects-most likely because they were done during summer when my shed is HOT AF inside.

Amine bloom is when components within the epoxy resin react with the air to produce a waxy oily substance on the surfsce of the cured resin. It is worse in cool and damp conditions EG my garage in winter time with the drier going (doh!!)

The bad news is that this substance will not allow paint or resin to bond with the underlying resin

The good news is that its water soluble and comes right off with soapy water and a scotchbrite pad. 

Just something to keep an eye out for! 

 

[Roman]

That turned out so good! 

Cant believe you managed to do that in-car without making a hideous mess haha. 
 

[flyingbrick]

haha,

Should see what it looks like now with the final layer!! (will save pics until i have done the other half)

I did the last half out of the car. I just wanted to make sure nothing warped for the first few layers.

Also.

You should see my garage floor under where i do this..

Its like there was a circle of asian men and my trolley was a school girl.

 

[flyingbrick]

So theres still much to do but i have the bulk of it done. Heres pics during its first test fit into the car. And my other plastic welded gauge cluster is having a mold made from it now because why not

[Ghostchips]

Is carbon fiber conductive? I would make a coil housing from it but suspect it might arc constantly and not work.