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I Need Some Help - Newbie Alert - Pics - FAIL!

Author	Message
ChrisR	ChrisR posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 363, Visits: 3K	Doh, its so long since I've done wetlay like this I'd forgotten about this layer!! With vac bag you should use a perforated film, it helps get the air out from under the film, you can use a release film directly onto the top layer but you have to be extra careful about creases and folds as this will be replicated on this layer. I'd recommend you keep using the peel ply then add a perforated release film on top of that separating the breather fabric. With regard to the amount of resin, aim for about 50/50 resin/fibre so weigh your fabric prior to mixing the resin (on such a small part you may just be weighing out a "minimum" quantity of resin i.e. 100g resin / 35g catalyst (or whatever the ratio is for that resin) you need to do this as a small batch of resin may not get the right ratio and/or not get mixed properly. Again, with such as small part it may be better to try two ways of doing it: 1) preimpregnate the fabric prior to layup - this might sound strange but just get some old vac bag and roll out your fabric and work the resin in, it will be more stable when applying to the mould and you can then work the first layer onto the mould surface well 2) Make the 1st layer so resin rich it's practically swimming, the second layer the rest of the resin, the third layer dry and gently pressed onto the 2nd then peel ply. The vacuum will suck the resin through the last layer. But also, to minimise voids/bubbles you will need to work on your technique in mixing and applying to the fabric - there's quite a lot of info on this here in TC and around the web/youtube dbcrx (05/03/2015) Another option would be to use a non perforated release film instead of the peel ply. This way you would get a shiny surface inside too, but all the resin you apply would stay in the laminate which may make it heavier than needed.
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*VVS*	*VVS* posted 10 Years Ago HOT Post Details
Group: Moderators Posts: 226, Visits: 334	Like you I'm fairly new to this but am a little few down the road having done some similar small wet lay and bagged parts with same end results. like the seasoned guys said use perforated film and plenty of play in the bag but I also found lots of vacuum made things worse and alot of cloth or peel ply hanging over the edge didn'thelp, this can get caught in the bag vacuum and then this stops it being pulled down onto/into the mould. I kept the vacuum low until I was happy with the cloth contact
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Zorongo	Zorongo posted 10 Years Ago Post Details
Group: Forum Members Posts: 40, Visits: 330	Use less resin, on second and third plyes, as you just don't need it. Just wetting them is enough. If the breather gets saturated by resin, it'll stop driving vacuum. The perforated limits the resin's flow between the part (it´s peel ply) and the breather. There are diferent hole sizes and space between holes, depending on your needings. It also acts as a barrier, making easyer to pull the breather off the peel ply once resin´s cured.
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dbcrx	dbcrx posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 46, Visits: 1.2K	The peel ply is different from the film he is talking about. You use the peel ply first which will release from the part leaving you a "bond ready" surface. But the peel ply will let resin through which will then be soaked up by the breather. Putting the perforated film between then peel ply and breather will just allow a small amount of excess resin through. Another option would be to use a non perforated release film instead of the peel ply. This way you would get a shiny surface inside too, but all the resin you apply would stay in the laminate which may make it heavier than needed. Regarding the mold - as said above it looks like the corners are very sharp. Fibers don't like tight 90 degree bends - you might need to consider redesigning it. The surface finish also comes from the mold. If your mold doesn't have a perfect gloss finish, then neither will the part you make from it. Edited 10 Years Ago by dbcrx
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MovingOn	MovingOn posted 10 Years Ago Post Details
Group: Forum Members Posts: 3, Visits: 41	Thanks for the replies and support! Chris - working on the items you outlined. Going to lay it up now. Matthieu - I have a layer of: Nylon Peel Ply .004" thick.
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Matthieu Libeert	Matthieu Libeert posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	I think I've found your problem reading your description in your way of working... You've forgot the perforated film... if you are not using it the breather will suck out "all" of the resin. The perforated film will ensure there is still enough resin in your part and only the excess resin is sucked out by the breather. Give it a try and let us know how it went Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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ChrisR	ChrisR posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 363, Visits: 3K	Hi, don't feel too bad, I reckon thats a pretty good go for a first time! Forgot the plexiglass, you don't need it. Envelope bad the thing and move on! Make the bag much larger than the piece so the breather can extend out and you can fit the connector in away from the p[art (like you did on the last picture) The part has a very tight radius so I would consider (unless it has to be like that for a reason!) make a flat sheet the correct thickness then cut the shape out or use something like profinish (or another bound fabric) and cut out a series of shapes to fit directly into the mould. If you intend to carry on as you are you need to make sure the 1st layer of carbon is firmly pressed into the corner and when you put the bag on it you need to give it lots of crinkles to allow it to confirm to the mould shape. Another way would be to cut out a flat plexiglass part that fits into the mould and put this on top of the final carbon layer, then encapsulate in breather etc... The matt side is the peel-ply, there is no way of getting rid of this (straight out of the mould) unless you use something like the plexiglass aforementioned. Post cure just give it a quick sand down smooth and a quick coat of lacquer and it'll be nice and shiny
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MovingOn	MovingOn posted 10 Years Ago Topic Details
Group: Forum Members Posts: 3, Visits: 41	Hello all~! As you are about to see - I am very new to making carbon fiber parts. I have a sailboat that I need to make some fairly large pieces for and right now just can't get out of the gate! One issue after the other and I'm sure it is all on me. I've vacuumed bagged multiple pieces and they all come out the same, shitty. The carbon fiber doesn't form to the mold very well and carbon itself is very dry - like the resign was sucked out of it. What I did in this latest fiasco was: Mold release Mixed the epoxy and put a thin layer - let it sit for 20 minutes (using 207 hardener) Laid the first 200g carbon fiber cloth on - put a lot of epoxy. Laid the second - put a lot of epoxy on - and then laid the third and final - with more epoxy. Placed a piece of peal ply. Placed a breather cloth. Put on the vacuum bagging and attached. Before the real crappy end result I have a few questions: Could my vacuum pump be pulling too hard? It isn't huge but maybe a little too big for this job. It is a 5 CFM 2 stage 1/3 hp Robinair. Tons of resign ends up in the breather cloth... The Carbon Fiber feels very dry and has a mate finish. Is there a specific number I should pull instead of letting it drop all the way to 30? The carbon fiber doesn't get down in the corners very well - comes out of the mold rounded with just resign in the corners. Could the breather cloth be too thick? Or am asking my setup to do something it just can't. Thanks all for your comments / suggestions / jokes. Communities like this make the world a hell of a lot better as it gives people the confidence to go out and do somethingthey never thought they could! This was the first go - and the plexiglass we had under it was way too thin and bowed. We have a gauge and regulator on the new setup that we used for the above hosed pieces.
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