Slimy38
|
| posted on 16/2/12 at 08:47 AM |
|
|
Opinions on a method of panel build
I wonder if I could get some thoughts on a method of panel build that I'm planning on. It's a process that has been inspired by this;
http://www.carbonmods.co.uk/Products/Carbon-Fibre-Skinning-Starter-Kit__CMCFSK300.aspx
This skinning kit doesn't use a mould, it's a decorative coating on any surface.
So, the plan is for the following;
- A layer of resin on a male buck (already prepped with PVA).
- 300g Fibreglass laid on to the resin when sticky, worked in with additional resin (normal fibreglass layup)
- Second layer of fibreglass in the same way. Leave to cure.
- On the ROUGH side IE without removing it from the buck, apply the laminating resin
- Carbon fibre sheet on the resin as described in the skinning kit
- Build up a couple more layers of resin to provide the gloss surface
- Leave to fully cure
- Use progressive grades of sandpaper to bring up to a glossy surface
- Remove from buck
I'm hoping that I'll end up with a decent surface, but I'm not 100%. I'm thinking that the sheet of carbon fibre and the three
surface layers of resin should be sufficient to 'flatten' the rough surface of a GRP panel.
I've bought a few supplies to make about half a dozen A4 panels for practise, and I'm also making it doubly hard for myself by going for
this as a surface material;
http://www.ecfibreglasssupplies.co.uk/p-1817-silvershadow-t-290g-twill-weave-1mt-wide.aspx
I'd have actually already given it a go if I had somewhere half decently warm, my limited experience with resins is that they really don't
like cold weather!
|
|
|
|
|
plentywahalla
|
| posted on 16/2/12 at 09:17 AM |
|
|
What type of resin are you planning to use? You need Epoxy for Carbon Fibre, but it won't dissolve the emulsion used to bind the glass fibres in
chopped strand mat.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
Slimy38
|
| posted on 16/2/12 at 09:44 AM |
|
|
I have two different types of resin to match the materials, I can't remember off hand what I bought but I was aware the materials needed
different properties.
It's also partly why I think I need to stop at the fibreglass stage, let that cure and THEN do the carbon fibre layer. I have no idea what the
two types of resin would do with each other if they're not allowed to cure, but the laminating kit does talk about it working fine on GRP so I
assume once it's cured it's 'safe'.
|
|
|
twybrow
|
| posted on 16/2/12 at 10:00 AM |
|
|
YOu will never get an A1 surface, as your rubbing down will inevitably rub into some of the carbon plys, but it can be a useful method to build a one
off....
A coat of lacquer can make it look more 'finished' than if you just try to sand it to a gloss finish.
|
|
|
Slimy38
|
| posted on 16/2/12 at 10:08 AM |
|
|
I get the impression that the additional coats of resin on top of the carbon fibre will give me more scope for rubbing down before getting back to the
fibre? I'm only doing one layer of fibre, but three layers of resin.
When you mention lacquer, are you talking about a two pack spray lacquer?
|
|
|
snakebelly
|
| posted on 16/2/12 at 10:18 AM |
|
|
Slimy, we're not too far from you, ternhill, and have been vacuum bagging cf panels for the gta, u2u me your tel no and I'll give you a
call, it may be worth you coming over to have a look
|
|
|
Slimy38
|
| posted on 16/2/12 at 10:49 AM |
|
|
Ooh, now that's a very welcome offer! It's the GTA that has 'inspired' me to look into this sort of thing, I'd love to
see what you're doing with it.
|
|
|
plentywahalla
|
| posted on 16/2/12 at 11:09 AM |
|
|
If using polyester first then epoxy, the poyester does need to be fully cured as you say, at least 14 days at a decent temperature. You would get the
best final finish if you did the fairing BEFORE the carbon laminates rather than after.
The twill weave will show every undulation in the sub-surface. Let the polyester fully cure then apply an epoxy filler or fairing compound, flat that
off then laminate with the CF.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
Slimy38
|
| posted on 16/2/12 at 11:43 AM |
|
|
quote:
Originally posted by plentywahalla Let the polyester fully cure then apply an epoxy filler or fairing compound, flat that off then
laminate with the CF.
Mmm, that sounds quite reasonable. I'll add that to the sequence, thanks.
|
|
|
ashg
|
| posted on 16/2/12 at 01:19 PM |
|
|
Watch this i filmed it at stoneleigh last year.
http://www.openfilm.com/videos/ckc-workshop-stoneleigh-2011-carbon-laminating
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
|
|
|
Slimy38
|
| posted on 16/2/12 at 01:31 PM |
|
|
Excellent, thanks. It starts off with a comment about resins that I didn't realise, and which will save me money. It's saying that
polyester resins will work with carbon fibre, but at the expense of ultimate strength. As I'm using it as decoration rather than as a structural
layer, I might try the polyester rather than the epoxy.
I'll carry on watching it tonight while the other half watches her soaps... 
|
|
|
plentywahalla
|
| posted on 16/2/12 at 02:19 PM |
|
|
Its not just the strength of Epoxy that's an issue, its also clarity. Epoxy laminating resins are completely transparent and allow the weave to
show at its best.
If you use a standard polyester laminating resin it will not be clear but tinted green or blue. When catalysed it will turn brown. How brown depends
on the amount of catalyst and the temperature it is allowed to reach as it cures.
I don't know how large a moulding you are planning to make but it would be a great PITA if for want of a few quid of decent resin it ended up
looking cr%p.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
twybrow
|
| posted on 16/2/12 at 02:32 PM |
|
|
Although polyester is arguably easier to work with at home.... It is far more tolerant of mix ratio. But agreed - epoxy is the superior choice with
carbon.
|
|
|
Slimy38
|
| posted on 16/2/12 at 02:35 PM |
|
|
Yeah, good point. I must stop being a complete and utter skinflint!!
|
|
|
Neville Jones
|
| posted on 16/2/12 at 05:42 PM |
|
|
A couple of points need clearing up...
Yes, you can use poly resin with carbon, just don't rely on the strength. I've done so for many years for cosmetic items. Use a lot of
vinylester as well. And you CAN use epoxy with chopped strand glass mat. See previous. It's done in the boatbuilders around here all the
time.
Poly resin isn't clear. Since when? Some cure water clear, some any colour from straw/lager colour to browns. Water clear is also available.
Same for epoxies.
Putting csm on then carbon then resin to flat back and polish is a non starter. That layer of csm will have more ripples and bumps than the fat lady
at the circus's backside. Any filler you put under the carbon layer will show through the carbon weave. Best to put a layer of tissue over the
base, wet out with black pigmented resin, then quickly get the carbon over that, then the resin.
I'd take the time to do a proper pattern and mould, it's worth the effort.
Cheers,
Nev.
|
|
|
Slimy38
|
| posted on 16/2/12 at 06:53 PM |
|
|
Thanks for the comprehensive reply Neville. The carbon (or more specifically the silver weave that I bought a sample of) will be purely cosmetic, it
will be good old CSM to provide the structure. If the panel is too weak, I'll be adding CSM to the back rather than carbon to the front!
You mention the resin showing through the cloth, and it's something that the video also picked up on. That is one thing I hadn't
considered. When I first tried fibreglass many moons ago, the resin that came with the pack cured to a bright orange, if that shows through the fabric
it is going to be hideous! What the video suggested was a cheaper fabric to provide a colour base, then the 'show' fabric on top.
It's also interesting you mention tissue. EVERY fibreglass tutorial, webpage, youtube video etc all say never bother with tissue. But I could
never figure out why that was. To my untrained eye it is a finer fibreglass used for surface finishing, and as such it's structural benefits are
significantly less than CSM. What you're saying about it being used as a filler coat along with a coat of resin makes sense.
I think I'm going to try a few options. I have about a square metre's worth of everything (although I'll need to buy a small amount
of tissue), so I'm going to make a few A4 sized panels using various sequences. So first my original plan, then one with a resin filler, then a
resin plus tissue filler. That will show the effect of working with the rough side of CSM. I'll then try several layers of resin on the top of
the fabric to see what needs to be done to get it to a smooth finish (if it's at all possible).
With regards to the mould, I still have it as plan F or G, but I want to try this method first. Apart from anything this will give me practise with
fibreglass for when I do the full monty!
|
|
|
snakebelly
|
| posted on 16/2/12 at 07:16 PM |
|
|
We are using 3mm foam core with 2 layers of 375gsm ttwill weave either side and it's incredibly strong. I do have some fibreglass cloth knocking
about that would add more substance than tissue your welcome to a bit for testing if you want
|
|
|
plentywahalla
|
| posted on 16/2/12 at 09:37 PM |
|
|
quote:
And you CAN use epoxy with chopped strand glass mat. See previous. It's done in the boatbuilders around here all the time.
I didn't say you cannot use epoxy with csm. I said that it does not dissolve the emulsion. Dissolving the emulsion allows the fibres to move and
the sheet follow complex shapes on contours. This does not happen with epoxy. This combination is only suitable for flat or gently curving
profiles.
P.s. I am a boatbuilder!
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
Neville Jones
|
| posted on 17/2/12 at 01:49 PM |
|
|
quote:
Originally posted by plentywahalla
quote:
And you CAN use epoxy with chopped strand glass mat. See previous. It's done in the boatbuilders around here all the time.
I didn't say you cannot use epoxy with csm. I said that it does not dissolve the emulsion. Dissolving the emulsion allows the fibres to move and
the sheet follow complex shapes on contours. This does not happen with epoxy. This combination is only suitable for flat or gently curving
profiles.
P.s. I am a boatbuilder!
I don't know what resins and mat you are using, but the stuff I have here has no problems with laminating, and 'moving' the fibres
about. If anything, the opposite. I buy from Scott Bader, who manufacture in India, so on the cheap, but good quality materials.
A boatbuilder you may be, they are trained to work in wood, as my grandfather taught me. My family also built motor bodies, ambulances, buses, trucks,
fire engines and buses, alongside grp boats since the second war and previous.
The 'emulsion' you mention, can be plain old starch, or a starch/kaolin mixture, or just plain kaolin(white clay). No high tech chemicals
involved. All info from Scott Bader tech reps. All binders are compatible and happy with epoxy. Whereas, not all higher strength fibres live happily
with poly resin, or even all epoxies or phenolics, kevlar to name but one.
Cheers,
Nev.
|
|
|
plentywahalla
|
| posted on 17/2/12 at 07:03 PM |
|
|
Well Nev ... This is getting a bit personal.... To answer your question we use West 105 and SP Ampreg epoxies and Ahlstrom cloths.
Read what West say about Epoxy and CSM. http://www.westsystem.com/ss/chopped-strand-mat-epoxy/
There are two different types of CSM. The most commonly used is emulsion bound. There is also powder bound which it sounds like you are talking about.
That would wet out with epoxy but we never use that stuff because it is very difficult to handle and get a decent uniform lay-up with compared to
emulsion bound. It would not be suitable for the OT's purpose as he was looking for a smooth finish for skinning with CF.
I used to build flybridge motoryachts
Here's one I made earlier!
[img]
 
Sealord 44
[/img]
Cheers
Richard (MRINA)
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
Slimy38
|
| posted on 17/2/12 at 08:04 PM |
|
|
That west link talks about release fabric, which I've managed to follow a trail to something called 'peel ply';
http://www.ecfibreglasssupplies.co.uk/p-374-peel-ply-1-mt-wide.aspx
Would that help with getting a smooth surface?
|
|
|
plentywahalla
|
| posted on 17/2/12 at 08:29 PM |
|
|
Epoxies should be overcoated within 48 hours as the amine comes to the surface and act as a very efficient release agent. This can be overcome by
using peel ply which can be left on the surface if overcoating is longer. It also allows surplus resin to be removed as carbon cloths should not be
over resinated.
It would help with your project. You usually have to purchase a whole roll. If you cannot get hold of any I can post you some.
Rules are for the guidance of wise men ... and the obedience of fools. (anon)
|
|
|
Slimy38
|
| posted on 17/2/12 at 08:43 PM |
|
|
Looks like East Coast sell it by the metre so I'll tag a bit on to my next order, thanks for the offer though.
|
|
|
Neville Jones
|
| posted on 17/2/12 at 11:48 PM |
|
|
quote:
Originally posted by plentywahalla
Well Nev ... This is getting a bit personal.... To answer your question we use West 105 and SP Ampreg epoxies and Ahlstrom cloths.
Read what West say about Epoxy and CSM. http://www.westsystem.com/ss/chopped-strand-mat-epoxy/
There are two different types of CSM. The most commonly used is emulsion bound. There is also powder bound which it sounds like you are talking about.
That would wet out with epoxy but we never use that stuff because it is very difficult to handle and get a decent uniform lay-up with compared to
emulsion bound. It would not be suitable for the OT's purpose as he was looking for a smooth finish for skinning with CF.
I used to build flybridge motoryachts
Here's one I made earlier!
[img]
Sealord 44
[/img]
Cheers
Richard (MRINA)
Personal??? Not even a dribbling contest.
It appears that your experience differs from normal practices on the south coast, as used by some very prominant builders of very large yachts, who I
do consulting work for on occasion.
Oh, and I put SNAME at the end if I want to be posh. My bro-in-law is top bod of RINA in a state in Aus. Never went past grade 8 at school, and got
where he is with the Masons and by being an instructor at the boatbuilding school. So please, give us a break and leave off with the implied
impression that you have some sort of superiority. Anyone who's paddled in the sea can get MRINA if he knows the right people, means nothing in
the great scheme of things, just like my letters. Unlike my bro-in-law, I've got a lot more letters from a lot more years of education, and the
calloused hands and arthritic joints from putting it to work practically.
Cheers,
Nev.
|
|
|
RK
|
| posted on 18/2/12 at 12:50 AM |
|
|
My issue with the poly resin is that it STINKS, whereas the epoxy doesn't. Enough for me to pay more for it, especially in winter.
And thanks, Ash, for that vid, for those of us who can't attend Dickens' events (but wish they could.) He really knows how to put it in
the normal person's language, as it were.
[Edited on 18/2/12 by RK]
|
|
|
