:party: ya ho ! getting better ever day…well done !
Still looks like not enough resin, are you using same weight of resin to cloth weight (+ 10% for carbon) ? thats rough hand lay-up formula, not sure if it is the same for vac, thought it would make no difference.
Be carefull with the pot-time of the resin (spec sheet) leave it too long before vacuumming, it may not vac if gone past green phase of curing (waiting couple of hours sounds excesssive to me :scared:) but depends on what the resin spec sheet says .?
Cheers Alan
Note: Just looked up the resin your using, L with harder EPH 500 and says processing time is 60 mins (pot-life) I would not wait longer than this to start vacuuming as the expoxy starts to go-off by then.
Iideally I would guess 45 mins would be time (read latest) to apply vac pressure, as it would help impregnate the cloth while is still in a workable state, if you start later may not be as effective.
I think the problems this time is due to the final glass layer was not wetted out properly.
I spend much more time laying it all up, and make sure everything was wetted out. Waited 1 hour to turn on vac. Seemed to work well still got some resin out in the breather…
Also today I laminated the plug with a layer of glass. Soon there will be mould making on the program.
BUT… (feel stupid not to have thought about this before now) Epoxy and safety?
I know to use gloves, but what about ventilation and/or respiration protection. Yesterday I had a little headache, but didn’t give it much thought. (Also having trouble with some tensions in my shoulder, so thought it could originate from that). But as I got the same headache today, i figured it was no coincident.
I had read the safety data sheet for the resin L which was available in english from r-g website. It says something about adequate ventilation, but when is the ventilation adequate? I guess mine was not as I got a headache. :scared::scared::scared:
The hardener datasheet was not available in english but foolishly assumed it was the same as the resin. But after the headaches I had a look at the german data sheet, with help from Mr. Google. And this seemed to be a little rougher in the wording…
For now all epoxy work is stopped until I get this straightened out… What do you do to make sure you have enough ventilation and stay safe???
I’m thinking I will buy a mask with A1 or A2 filter in it to be on the safe side…
Previously I used West Systems epoxy and didn’t experience any problems working the same way I have been the last few days, West systems is more than double the price of r-g products, but if i remember correctly they are also Loyds approved.
I just pulled the 4th attempt out of the mould with good results. :icon_tong
Weight is 26g compared to the calculated 28,5, which I think is not bad…
I thought I would try to apply two layers of perforated film in an area, to try to reduce the number of holes, knowing it might totally block the “flow” of resin… which it did, so surface not so good in that area, but now that lesson is learned.
Still some minor problems here and there, but I am satisfied with the result. Also struggling a bit with the edge I have in the wide end of my test mold, which will not be there on the complete hull mould. Also all see-through pinholes are eliminated…
I would say I am ready to go all in for a complete hull now. I think the most important lesson I have learned is to be very thorough, when you think it is good enough go over it again… and a pot life of 45-60 min. is not that much…
When going full scale, I will take Alan’s advice and mix a pot for each layer.
Today I will only be doing some woodwork, as I am still a bit spooked about the headaches. Will try to buy a gasmask today, if I can find one…
Anders a huge improvement & looks like you have everything just about nailed, was very good idea to test sections rather than experiment on full hull laminations …well done.
Not much I can offer on the safety question, good ventilation I would take as at least and open window if you wroking in closed room, I work in open workshop hence have not experienced any problems and I normally have most of my lamination completed in under 1 hour, then I’m sailing or doing something else.
I suffer from instant headaches from time to time, but found it was mainly to do with big swings in atmospheric pressure, Low pressure system changing quickly into a high pressure system, here my release value is not working so good as I’m getting older :lol: but if you are concerned, would not hurt to see doctor, it’s worth the piece of mind…just be careful when he starting stretching those latex gloves over his hands and askes you to bend over …
Pains in shoulders etc, I have them too when working on the bench planking of drying fittings parts inside the hull and when & thinking too much about different things adds to physical stress that shows up in the shoulders and neck, pays to have cool beer near-by (well that’s my excuse :rolleyes:)
I could never wear gloves working with epoxy, personal thing, where I like to feel what I’m working with & at the end of the day I work with such small quantities and infequently, I don’t even think about it, but I do use hand barrier cream. When cutting or sanding glass of carbon fibre I always wear basic face mask, breathing in this stuff cannot be good for the lungs.
Relax & take your time, I personally found what works for me is to write a quick check list of things that I need to do, in sequence and then set myself the target of completing one step each day, then progress is quick and I spend less time farting around and then feeling like I achieved nothing.
I got a mask today with A2P2 filter in it. So will use this to be on the safe side. Temperatures here in DK is getting close to 20 degrees so will do the layup and other epoxy work in the garage opening, and move the hole lot to the heating room for vac.
I had a window and door open in the heating room, but seems it is not enough ventilation. I’d rather be on the safe side.
Maybe I will apply a layer of resin to the laminated hull today, so I can start wet sanding… tomorrow or friday.
There has been a big jump in the proceedings since I last had a chance to drop by.
I have a couple of additional things to add-
Personal protection… You may or may not be surprised to learn that Latex gloves offer little protection to epoxy resins.
You should always use Nitrile gloves.
This is because the Poisonous gases are able to penetrate latex, the skin and then into the bloodstream but not when using the nitrile barrier.
I always use a base layer of nitrile, then add a “sacrificial” layer of latex gloves over them that get changed as required as this is a more economical form of protection.
As I am in contact with resins on a day to day basis, becoming sensitized would be nothing short of a disaster.
The vapours have a toxic component, but wearing a mask usually combats some of the affects.
This is not a total safeguard.
Correct ventilation is the only answer.
West Systems ProSet is just about the best resin system you can get… It is a Phenolic free sysem. Phenols are the primary reactive in most Epoxy resin hardeners and the cause of the burns if you get it on your skin… That is the only resin system we used on Ericsson 4 as the secondary bonding/wet layup. Once post cured correctly the characteristics are not that dissimilar to pre-preg.
Now to the subject of ‘Double Perf’…
If you put perf to perf, then the holes become blocked, this is a fact.
The common practice is to use a layer of breather to separate the layers.
Breakdown is as follows:
This technique allows the excess air and resin to flow between the control barriers (perf) and the absorbent carriers (breather)
However, there is no such thing as a free lunch. You run much higher chance of wrinkles and creases in the laminate using a bigger, double`vac stack’… So approach with extreme caution - We are fast approaching some very technical vacuum stack procedures that really are way over the top for a couple of layers of carbon…
Lets walk before we run!
I’d like to share this thought about the best lesson that can be learned thus far : Is that Vacuum does not fix laminating flaws. It serves to highlight them…!
My feeling is - There is nothing wrong with the system you have, I feel that perfecting the laminating technique will achieve the result you are striving for.
Hey buddy, been 4 weeks since you started wet sanding ? … did you sand it away or what ? no really I’m just a liitle worried that you were not feeling well at the time … and only like to check-in to see that you are ok ?
I’m still alive and kicking; only problem is that I have no more holiday.
Haven’t been wet sanding for 4 weeks, even though it felt like it. It is just a very slow process.
I have made some progress, and next step will be to make the mould. The plug is waxed and ready. But temperatures here in Denmark went down around 5 degrees, so have to wait for warmer weather before I can take the next step. I will not work with epoxy indoor again.
I have had to make some edges all around the hull, to give me the mould shape i want, sides are wedged in place end ends are screwed in. This way all the edges can be removed, when removing the mould from the plug, which I hope will make it easier.
The weather forecast says 20 degrees this weekend so maybe I will go for a mould then. Problem is, that good weather also makes other things like mountain biking and kite surfing more interesting, so it is all a compromise when you have to many hobbies
Great to hear all is well the mould looks great well done !
After high twenties here last 2 weeks …temp dropped down to -3 here last night, crazy weather patterns uh !
All the best that you can fit in moulding this weekend & have opportunity for other things on the wild side of life …we are here for a good time, not a long time … make the best of every day buddy
I had a go on the mould during this week. Even though I had some problems, the result is okay. It looks terrible, but the inner surface is actually pretty smooth, just have to buff it up and I guess it will be shining. Pictures are right of the plug. Next time I think I have to try Jim’s plaster(ish) method, as it seems easier and cheaper, but this was the way I knew and had tried before.
After applying the first layer of epoxy with graphite powder to make it black, I thought I would try the plastic lay-up method to practice. But as I waited about 2 hours to let the first layer gel up, it was sticky as h… So as soon as the fibers touched, it was stuck. I decided to rip it of again and apply small pieces in stead. The ripping-of caused some of the black resin to come along, which is why there are some white spots.
Now I have to reinforce the mould a little more, then I am ready to go for the first hull.
I have come I doubt if it is necessary to have the outer glass layer (to avoid pin-holes), when also using vacuum? It will add a good 50g to the hull, and I think not contribute much to the stiffness.
Too bad about that - but it is true it is a “Rich Man’s Sport” - unless Lasers would be selected. Once sponsorhip was allowed the arms race started in as the owner didn’t have to foot the entire cost of a campaign by himself. He who could find the deepest pockets had a better chance than those who couldn’t find a sponsor.
I think (opinion) this would be true in r/c sailboats as well - everyone would be purchasing/racing a Scalpel (as example) if someone else (a sponsor) were paying the bill.
Good question, havent thought about polyester, I have only worked with epoxy, but I dont think there is any good reason not to use polyester…
But next time I will for sure go foir the plaster in stead. Then I don’t have to do all that crazy wet sanding. Then the steps would be: Plug in wood or foam… Wrap it in packing tape… Make the mould, and you are ready to start all the funny work. (There might be a little more to it, but i bellive it is much faster approach). For this project I must admit that I have been a bit concervative, only using techniques I knew, in stead of taking up some of the great ideas posted in here.
I am not far from making the first hull now… I think it is only a matter of days in fact. Just need the temeperature to come back up…
Polyester not only smell bad but has another defect, it contract around 2-2.5 %.
This was my esperience of several years ago .
The first time I discover that was during the manufacturing of the female mould of my Tuiga. This mould was supposed to be in two parts.
After demoulding of first half I spent about a week before starting the second half. The idea was to put back the master into the first half mould and use it as support for the second moulding.
Surprise !!!
The master was not entering the half female mould anymore !!
The measurements proved that the half polyester mould was shorter of 3.5mm out of 1540 mm hull lenght , compared to the master !!!
I got confirmation from my composite supplier that indeed the polyester contract during polymerisation that can be considered completed after a week.
Since then I never used Polyester resin again !
Cheers
ClaudioD
I’ve never noticed shrinkage. That doesn’t mean it doesn’t happen. I pop the mold off the plug a few hours after lay-up just because I’m impatient to se how it turned out. Then I clamp them back together for 4 or 5 days or more. I have noticed that the mold will warp(close up like clam/lessen the beam slightly) if I don’t do this. After the week I take them apart and never put them together again so I don’t know if it shrinks/warps any more. I’ll dig out an old plug and mould and see how they fit.
Don
I checked two. One fits fine and the other has opened up a bit. I normally put plywood reinforcement on while it’s cureing but I didn’t on the one that opened. Lesson learned. Length wise they are fine.
This has made me wonder why I still have the plug and mould of a boat I will never build again:confused:
Woop woop… first hull is laminated. Not the best result, but I bellive it is useable. Will properly try to do a better job.
But to start with the mould. I reinforced it with epoxy mixed with generous amount of dried beach sand. Can’t remember where I picked up this technique, but it works perfectly.
Now back to the first hull. I am almost sure the problem is caused by applying too much vacuum. I took my time wetting out the layers and arranging them in the mould, so it was almost 3 hours from when the first batch of epoxy was mixed, to the point where I closed up the vacuum bag. This made be believe that the outer layers had gelled up, and therefore could handle a little more vacuum. I used 0.55 mbar for the hull, which is actually quite stupid, as I achieved the best results in my tests with only 0.3mbar.
The predicted weight of the hull is 280g and ended up at 220g, which I think supports my theory about too much vacuum applied. It seem so have good strength.
Another problem area is all around the edges. I can see that it is necessary to trim the fibers along the edge before putting it in the bag. It doesn’t work when they have to bend around the edges. Any tips on trimming along the edges would be appreciated. Is it best done with some special scissor or a hobby knife?
Will continue work on deck mould and internals asap, (which is not that fast… ) little progress is better than no progress.
WoW :party: well done Anders …love the idea of using beach sand mixture for female mould
I’m surprised you waited so long (3 hrs) before you bagged it & would suspect this would have been the main cause of any problems, but I say that with have no experience wilth bagging, so wait for expert commentary from others.
For trimming I found scribing the shear line and then carefully using dremel with diamond cutting disc works easiest and then flat block sanding to clean it up.
I’m currently fitting out 120 hull now, if interested you can see what I’m doing here on Italian AC 120 site in the English forum http://iacc120cup.altervista.org/
I didn’t wait 3 hrs… It just took that long before I was ready to bag it… :lol:
I want to do the trimming before putting the mould and laminate in the bag. The bag will bend the fibres arrond the edges, which are sharper than the fibres can be bend, so the fibres are not pushed against the mould allong the edges. I kind of hoped the vacuum would be enough to make the fibers behave. But sharp edges is a no-go. (As I already knew)
Every time I f… up, I gain some experience… So in a way, I win every time! :lol:
) little progress is better than no progress.