SmudgerEBT
|
| posted on 1/6/16 at 07:26 AM |
|
|
Carbon Fibre - Making It Tidy
So I need to do some side vents (mid-mounted with rads in the back as no room in the front), I have a basic mould (which I need to reinforce and add
layers too) which I will use to make a wet layup part (whilst it would be nice to do vacuum resin infusion its not worth the outlay for a handful of
parts) probably using epoxy clear coat.
Now it has 3 lots of right angle, getting the cloth into those corners will be difficult without distorting the cloth and probably the odd void.
So my idea is to run black (or maybe green/orange) gel coat with a width of 5mm around the edges and into the corners, this means the carbon fibre can
be cut into a sheet (3 pieces) and as long as time is spent getting it to line up, should be easier.
But will it just look cheap part finished with the gel coat strips and with that in mind is it worth investing into vacuum resin infusion and get that
to force the carbon into the edges?
My car is Green, would it be to much to do the parts in Green Carbon?
|
|
|
|
|
bi22le
|
| posted on 1/6/16 at 08:19 AM |
|
|
I have never done carbon lay soy opinion is actually worth 0 but when watching youtube clips on this it actually seems quite easy to shape into
corners.
I use youtube to learn most car related things and there are loads of good bits on there about CF fabrication.
Personally i feel a slightly off weive would look better than green gelcoat and certainly less risk of breaking, unless you run the weive throught the
gelgoat aswell.
Maybe increase the rad to make it easier to form?
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
|
|
|
Neville Jones
|
| posted on 1/6/16 at 08:48 AM |
|
|
Wet layup and a bit of vacuum will do the job for you. Forget resin infusion as it ends up with resin rich/dry areas, and gets messy, and also wastes
far too much in consumables.
Done every day in the marine industry, and a lot of the times an ordinary household vac will be more than adequate, depending on resin.
Cheers,
Nev.
|
|
|
coyoteboy
|
| posted on 1/6/16 at 08:52 AM |
|
|
Could you not get a metre or two of prepreg, shape, vacuum and oven cure?
Personally I've never managed to get a decent finish on a wet layup without massive excess resin and hours of sanding.
|
|
|
Neville Jones
|
| posted on 1/6/16 at 09:02 AM |
|
|
quote:
Originally posted by coyoteboy
Could you not get a metre or two of prepreg, shape, vacuum and oven cure?
Personally I've never managed to get a decent finish on a wet layup without massive excess resin and hours of sanding.
That's the difference that 40+ years of experience gives. 
Beginners tend to overwet the layups, and don't roll out the layup properly, if at all.
Prepreg can introduce a minefield of problems. It can have anywhere between 35% and 45% resin, and the lighter end will definitely need a clave, and
even then will end up with pinholes in the surface.
The higher resin pregs are mainly used as surface.first layer, to get that pinhole free smooth surface then layup with dryer behind. Not something
for the budget conscious!
Tooling finish has as much to do with end result as anything else. Then there's release systems. Some will let the resin spread nice and smooth,
some quite the opposite.
Cheers,
Nev.
|
|
|
Theshed
|
| posted on 1/6/16 at 11:40 AM |
|
|
Can you not iron out the right angles with a fillet of wax? Look on the easy composites web site. I agree that it is a bugger to get carbon into a
right angle.
I am not sure many would agree with the suggestion that resin infusion is more likely to give resin rich areas than wet layup and a household
vac....
A household vacuum will pull 80 inches of water - about 3psi. A proper vacuum pump will (as it says on the tin) get close to a vacuum - so 14.7psi
That said I see no reason why a careful wet layup will not be both strong (enough) and good to look at.
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 11:44 AM |
|
|
Trying to do things on a budget (or as much as I can).
So wet lay up is cheaper than vacuum, no expense on breather fabrics, pump etc
However, just lay a sheet of carbon cloth in the make shift mold and vacuum would force the cloth into shape, where as wet lay up might not (not
without some weave going wonky), which with vacuum means I wouldnt have to have a band of gel coat around the edges to keep it pretty.
But if I invest in vacuum, that does open to do brackets for various things.
|
|
|
Neville Jones
|
| posted on 1/6/16 at 11:53 AM |
|
|
Resin infusion by its very nature and method, will give a rich area where the resin is introduced. Then there's the pitfalls for the unwary.
I've made nearly all the mistakes, but I'm sure there's a few that have still to come. It's not something for the amateur to
dive into, unless he is prepared for a string of mistakes. Then there's the waste, as I mentioned.
Vacs..Our shop vac will pull down to 120mb, our household Henry down to 200mb. Both way more than you need for wet layup vaccing. If your household
vac is what you say, you better get down to Argos and buy a Henry. Best home vac we've ever had! 
My pump for the clave is two stage and oil lubed to run constantly and give about as ultimate a vacuum as you can get. Not cheap, and definitely not
for a home hobbyist to consider.
Cheers,
Nev.
|
|
|
FuryRebuild
|
| posted on 1/6/16 at 01:06 PM |
|
|
Hi All
I disagree that resin infusion leaves dry and rich areas. It's one of the most reliable methods to get a uniform, bare minimum amount of resin
in the part. However, it is an involved technique and requires the correct equipment and you need to hone your technique. You won't properly
pull resin through a part with a household vac, and without a catch-pot you run the risk of getting resin in it. That's the end of the Vac. For
a reasonable part, it's not unheard of to pull vac for 30 mins or more just to get the resin through. A household vac would suffer with that
kind of duty cycle. Vacuum pumps are designed as 2 stage pumps so they can run for hours.
You only end up with a resin rich part if you let the resin run in after you turn off the vac. To do it properly, you have the mould and resin at
about 30C where the viscosity is then correct for infusion resin such that when the visible part fully penetrated with resin, it will have run all the
way through. If you are getting dry spots with cores, that's usually when the core hasn't been scored properly to allow resin travel
underneath - flow-mesh takes care of on top.
To get a structurally correct part, you get the resin fully flowed through, then shut off the feed and let the vac run until it gels off. This
guarantees the bare minimum of resin in the part. It also gives you the best chance of pulling out any air you've introduced. Infusion resin is
carefully designed for viscosity - once it's all in and wetted out, you have the correct resin/cloth/core ratio. Any more than that which you
need is waste. You do lose some to the tubing, flow mesh, etc. but that's still far less resin in the part than say wet-lay. Oven-temp non
autoclave pre-preg is an option, but it can be difficult to avoid pin-holes, and you still need a method to properly press the layers together into
one fused part (say vacuum) to avoid delamination. With resin infusion, if you are unlucky and get air in the part, you run a risk of pin-holes as
well. There are ways of being certain you haven't introduced any air. As I said, technique.
With regard to surface finish, it does depend on mould surface, keeping air out of the part, and release agent. PVA will get you a release from
anything, but it's hard to get a shine on it.
With regards to right-angles - don't do it. I generally run to a minimum radius of 10mm when making a buck for a mould (quadrant beading from
B&Q is your friend). If you try and get into right angles you will get bridging and it will look bad. If you need right angles, I would lay into
the mould in right angles, but then put a equilateral triangle of core material into the corner and put the backing layers in that way so you avoid
bridging. Bear in mind if you're using something like 200gsm cloth then you will need a minimum of 2 layers facing to avoid seeing whatever
backing layer you're using. You may still end up with dry spots this way.
I also use plasticene to make fillets, and then a filleting tool to push it in and simultaneously shape the fillet. East Coast Fibreglass sell this
stuff, and I have loads of spare plasticene. I'll post you a brick if you want.
I'd advise for 'on the cheap' just having a crack at wet-lay if you just want to have done it. It's the cheapest way in. For
a structural part, I'd look at infusion but you need to consider the cost of entry. OR ... find something out there that you like and buy it.
If you take a read of this blog post www.furyrebuild.co.uk you can see where I put a part and a couple of test
parts under the microscope to show air bubbles in a part and one where it was infused without any air-ingress.
[Edited on 1/6/16 by FuryRebuild]
When all you have is a hammer, everything around you is a nail.
www.furyrebuild.co.uk
|
|
|
Theshed
|
| posted on 1/6/16 at 01:35 PM |
|
|
err 200mb = just under 3psi
The other reason not to use a domestic vacuum is that they rely on air flow to avoid overheating. You could use a domestic vacuum to pull out the
majority of the air but that is about it.
Have a read here.
http://www.fram.nl/workshop/vacuum/
|
|
|
Vmax1974
|
| posted on 1/6/16 at 02:53 PM |
|
|
Where are you based i have my composites pump you could come and use if your north east
|
|
|
bi22le
|
| posted on 1/6/16 at 03:06 PM |
|
|
I fancy doing something like this but i get the gist that the best idea is to use GRP or fab from from ali and weld. . .
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
|
|
|
bi22le
|
| posted on 1/6/16 at 03:08 PM |
|
|
Actually on this topic can I ask a really silly question?
Most CF mouldinng is using a buck that you lay onto, the the contact netween the buck and the part is the outside of the finished part.
Can i make a male mould so i skin the buck with CF and then seperate. Will I be able to get a good finish on the outside still?
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 03:10 PM |
|
|
North West, Stockport (near Manc).
So could I wet lay then just vacuum (thru the ply etc) to remove excess resin?
Have seen that easycomposites do a cloth with resin impregnated already, so that will make it stay in one place a bit easier.
Now to get the rear arches and start sorting out the vents, so I can build then.
Will post a pic of an early attempt to show what I mean.
|
|
|
Vmax1974
|
| posted on 1/6/16 at 03:23 PM |
|
|
quote:
Originally posted by bi22le
Actually on this topic can I ask a really silly question?
Most CF mouldinng is using a buck that you lay onto, the the contact netween the buck and the part is the outside of the finished part.
Can i make a male mould so i skin the buck with CF and then seperate. Will I be able to get a good finish on the outside still?
The mould is just a polished negative of the final piece the finish you get is always the same as the mould if you spend thw time and effort when you
make the mould the less time and effort you need to put into finishing the final item
If you skin the buck with CF you will have to spend ages finishing the part and it will be about 2mm bigger than the buck due to the thickness of the
materials you use
Hope that helps
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 03:39 PM |
|
|
Am just waiting for easycomposites to confirm me on the forum so I can annoy them with questions.
Off to take pics of what I want to make, both in terms of mold and parts.
Pics will explain better than my co-codomol ramblings.
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 04:28 PM |
|
|
So looking at making a mould of this:
Would it be better to extend the part for the mould (for instance use playing cards taped up to give an extra 4 inch or so) or do it at right angles
and 2 part the mould?
Now in the center pic you can see the "ridge", now will the carbon go into that or deform? If deform its not a problem since just get it
painted green (with the rest of the car) and only leave certain sections showing.
Or just do it in csm & woven and vacuum that. The idea is to reduce weight a bit and if possible a bit of bling.
Now the vents:
Basic mould.
As you can see, some sharp curves, will the vacuum press the carbon into that with deforming or is my idea of running a (black) gel coat strip around
edges and the center joins a better idea?
|
|
|
Vmax1974
|
| posted on 1/6/16 at 04:42 PM |
|
|
The larger part with work could be moulded as 1 piece maybe use corex to make a flange all the way round
Laying the carbon i would lay it in sections maybe use a 2 inch tow as a racing stripe to separate the layers from one side to another
The vent could be made in sections or you could use the gel depending on your preference
|
|
|
Neville Jones
|
| posted on 1/6/16 at 04:52 PM |
|
|
The pressures I stated are ultimate, ie gauge. So 200mb is ~800mb below ambient, and not 3psi less than ambient. Maybe I wasn't clear.
There seems to be a lot of people with conflicting input. I just wonder, how many do this stuff for a living?
There's only one sure way of getting even resin distribution, and that's prepreg. Everything else is second best. Any man who suggests
resin infusion is as good as prepreg, hasn't done the resin content testing on finished parts. There is a well known composite company not a
mile away here, and they've tried everything, and have settled on prepreg and/or their own novel material system with vacuum. They tried resin
infusion, in all it's iterations, and customer tests on parts had them discarding up to 75% of parts. Customers include Rolls Royce and Aston
Martin. There was a boatyard in Lymington, who were sold the idea of infusion as far back as 1978. The results were sat out in the back of the yard
up until a few years ago.
Don't get me wrong, infusion has its place, but not anywhere in my work or workplace. I know tractor people who use it, and also
commercial/industrial/architectural parts makers who use it. All of which don't give a monkeys about resin content or rich/dry areas. All they
want is a quick cheap part, and that's what it gives.
Resin infusion with a home vac is not what I suggested either.
A wet layup, ie put the fibre in the mould then brush in resin without letting it pool, then peel ply (supermarket bag), then breather (wadding from a
clothing material store) and a bag made from heavy plastic ( or clear heavy duty bin bag, or heavy plastic from Screwfix for covering for painting )
sealed up with duct tape or any decent tape. Put the vaccuum on it and let it cure.
What's so technical and difficult about that? The only difference to what I wrote above in my work, is that I buy peel ply on 200m rolls, and
same with breather. Times when I've run out of breather it's off to the local dressmaking shop, for wadding. Same stuff. I do this work
just about every day and first learned it back in 1972, making helicopter blades in remote parts of the commonwealth, and doing wet layup work
boatbuilding for a lot of years before that. Anyone who can hand lay poly resin and get minimum content, can do any sort of laminating.
There's a lot of people on Youtube and the 'net who want you to believe that vacuum consolidation is a mystical art, it's not.
I'm writing this as I wait for an intake plenum to set in the moulds, and it's being made just as I wrote above, but with an old vac pump
and not a cleaner. Noisy old pump it is too!
At the other end of the scale, I use prepreg in autoclaves that I build myself from commercially available parts. Again, no great science, just
simple, practical applied common sense and engineering.
Cheers,
Nev.
|
|
|
Vmax1974
|
| posted on 1/6/16 at 05:04 PM |
|
|
quote:
Originally posted by Neville Jones
The pressures I stated are ultimate, ie gauge. So 200mb is ~800mb below ambient, and not 3psi less than ambient. Maybe I wasn't clear.
There seems to be a lot of people with conflicting input. I just wonder, how many do this stuff for a living?
There's only one sure way of getting even resin distribution, and that's prepreg. Everything else is second best. Any man who suggests
resin infusion is as good as prepreg, hasn't done the resin content testing on finished parts. There is a well known composite company not a
mile away here, and they've tried everything, and have settled on prepreg and/or their own novel material system with vacuum. They tried resin
infusion, in all it's iterations, and customer tests on parts had them discarding up to 75% of parts. Customers include Rolls Royce and Aston
Martin. There was a boatyard in Lymington, who were sold the idea of infusion as far back as 1978. The results were sat out in the back of the yard
up until a few years ago.
Don't get me wrong, infusion has its place, but not anywhere in my work or workplace. I know tractor people who use it, and also
commercial/industrial/architectural parts makers who use it. All of which don't give a monkeys about resin content or rich/dry areas. All they
want is a quick cheap part, and that's what it gives.
Resin infusion with a home vac is not what I suggested either.
A wet layup, ie put the fibre in the mould then brush in resin without letting it pool, then peel ply (supermarket bag), then breather (wadding from a
clothing material store) and a bag made from heavy plastic ( or clear heavy duty bin bag, or heavy plastic from Screwfix for covering for painting )
sealed up with duct tape or any decent tape. Put the vaccuum on it and let it cure.
What's so technical and difficult about that? The only difference to what I wrote above in my work, is that I buy peel ply on 200m rolls, and
same with breather. Times when I've run out of breather it's off to the local dressmaking shop, for wadding. Same stuff. I do this work
just about every day and first learned it back in 1972, making helicopter blades in remote parts of the commonwealth, and doing wet layup work
boatbuilding for a lot of years before that. Anyone who can hand lay poly resin and get minimum content, can do any sort of laminating.
There's a lot of people on Youtube and the 'net who want you to believe that vacuum consolidation is a mystical art, it's not.
I'm writing this as I wait for an intake plenum to set in the moulds, and it's being made just as I wrote above, but with an old vac pump
and not a cleaner. Noisy old pump it is too!
At the other end of the scale, I use prepreg in autoclaves that I build myself from commercially available parts. Again, no great science, just
simple, practical applied common sense and engineering.
Cheers,
Nev.
I have to agree i have been working with composites for coming up for 19 years now and prepreg does produce the best results i have cured prepreg with
a few bits of foil backed foam insulation board from bond and quale and a electric 3 bar heater and barbecue thermomiter it should be considered a
real contender for what you're looking for
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 05:09 PM |
|
|
Always interested in learning new things and ways.
So corex glued on the underside, all painted with (for instance) EasyComposites Pattern-Coat Primer followed with EasyComposites Pattern-Coat Hi-Gloss
then go with epoxy resin (for clear coat) carbon, carbon, carbon, carbon, breather etc vacuum pull?
Any cheaper Primer etc links please.
|
|
|
Vmax1974
|
| posted on 1/6/16 at 05:28 PM |
|
|
Imho Start with the vent mould first use plenty at least 10 coats of wax to get good reliease take your time and enjoy the process
The bigger part i would take it to a local bodyshop and say "paint that in whatever colour the next job is painted in" i get a lot of raf
grey like that as my neighbour paints aircraft for the raf then i would take a grp mould then "break that in" then pull the carbon from
that finish will be much better when your finished
Tip if you use a piece of masking tape push it against the waxed surface of the mould if when you pull it off if there is very little resistance then
there is enough release agent in the mould if in doubt add another coat of wax
|
|
|
twybrow
|
| posted on 1/6/16 at 05:50 PM |
|
|
quote:
Originally posted by Neville Jones
Resin infusion by its very nature and method, will give a rich area where the resin is introduced. Then there's the pitfalls for the unwary.
I've made nearly all the mistakes, but I'm sure there's a few that have still to come. It's not something for the amateur to
dive into, unless he is prepared for a string of mistakes. Then there's the waste, as I mentioned.
Vacs..Our shop vac will pull down to 120mb, our household Henry down to 200mb. Both way more than you need for wet layup vaccing. If your household
vac is what you say, you better get down to Argos and buy a Henry. Best home vac we've ever had!
My pump for the clave is two stage and oil lubed to run constantly and give about as ultimate a vacuum as you can get. Not cheap, and definitely not
for a home hobbyist to consider.
Cheers,
Nev.
Nev that is not correct unkess you cure with your inlet open to atmosphere. During thr infusion there will be a pressure drop between inlet at
atmospheric and outlet at vacuum. Once all wet out and before gelation, you need to shut off the inlet and the pressure gradient will equalise and
the resin rich areas should disperse. Once the inlet is shut, it is exactly the same as wet layup and vac bag.
The problem with sharp right angle corners is that the fibre will never want to take up that shape without some force (vac) to hold it into the rad.
It is better to fill out thise corners with filler to give you a larger radius rather than bodging with gel coat.
And in case you are unsure, yes, i do this for a living for one of the largest composite suppliers in the world - string and glue is the future!
|
|
|
SmudgerEBT
|
| posted on 1/6/16 at 06:02 PM |
|
|
quote:
Originally posted by twybrow
quote:
Originally posted by Neville Jones
Resin infusion by its very nature and method, will give a rich area where the resin is introduced. Then there's the pitfalls for the unwary.
I've made nearly all the mistakes, but I'm sure there's a few that have still to come. It's not something for the amateur to
dive into, unless he is prepared for a string of mistakes. Then there's the waste, as I mentioned.
Vacs..Our shop vac will pull down to 120mb, our household Henry down to 200mb. Both way more than you need for wet layup vaccing. If your household
vac is what you say, you better get down to Argos and buy a Henry. Best home vac we've ever had!
My pump for the clave is two stage and oil lubed to run constantly and give about as ultimate a vacuum as you can get. Not cheap, and definitely not
for a home hobbyist to consider.
Cheers,
Nev.
Nev that is not correct unkess you cure with your inlet open to atmosphere. During thr infusion there will be a pressure drop between inlet at
atmospheric and outlet at vacuum. Once all wet out and before gelation, you need to shut off the inlet and the pressure gradient will equalise and
the resin rich areas should disperse. Once the inlet is shut, it is exactly the same as wet layup and vac bag.
The problem with sharp right angle corners is that the fibre will never want to take up that shape without some force (vac) to hold it into the rad.
It is better to fill out thise corners with filler to give you a larger radius rather than bodging with gel coat.
And in case you are unsure, yes, i do this for a living for one of the largest composite suppliers in the world - string and glue is the future!
So would you say the orange pic is ok to do with carbon and vacuum?
|
|
|
Vmax1974
|
| posted on 1/6/16 at 06:17 PM |
|
|
I have made envelopes from vag bag and just put the part in that i can put my wheel arch and dash moulds in them as they dont have the edge to seal
the bag too so doing the same on that vent mould will be simple enough ,
|
|
|
