Vacume Infusion Layup Question

[Salmonid]

Hi,

I want to reinforce a rectangular hatch cover on my kayak to make it stiffer and to provide an additional surface for the gasket seal to contact (see picture). As it is, it leaks and is a bit on the flimsy side. My plan is to glass in a piece of 3/8" foam (Baltek) that is a bit smaller than the dimetions of the lid so that the rubber gasket will fit into the gap that is formed (see photo). I went to my local composite dealer (Fiberlay) and they convinced me to try Vacume Infusion layup. Being the sucker and tech geak that I am I figure it might be a cool method to mess with. I beleive I have all the requisite supplies and equipment and the basic undertanding of the process but I have a couple of questions for those who have tried this already. I was planning on using Enkafusion CX-1000 resin distribution medium which is about 4" wide. I am not quite sure how to set up the resin and vacuum ports for my hatch. For a simple flat pannel one would place one strip of Enkafusion on one end for the resin inlet and one strip on the oposite end for the vacuum fitting. Since my hatch cover is essentialy a tray and it will have a groove around the perimeter for the gasket recess I am not sure what the best thing to do is. At this point my thoughts are to place a piece of Enkafusion covering just the width of the Baltek foam core (narrow wise dimension) on one end for the resin inlet and a piece on the opposite end of the lid for the vacuum port. I would seal the bag just adjasent to the top of the rim of the exising layup of the lid so I can add a little structure and strength to the sidewalls of the lid. My only fear is that the resin (thinned epoxy) may not completely infuse the fiberglass covering the sides of the foam core, the floor of the groove and the sides of the hatch. Perhaps this will be fine especialy since it is a small area? I am also thinking of cutting the Enkafusion in half lengthwise due to the small sixe of the part, anyone done this? I will tape the exposed end and will use release film under the Enkafusion because I don't want it bonded to the layup. Also I am curious what peoples expeirnce has been using 3M 77 spray adhesive to tack the materials in place? I have heard mixed things about using this. One more thing I am wondering about is if it is advisable and what to use to fare the edges of the Baltek foam. There are some small imperfections in the sidewall of the foam where my cuts intersect with the resin grooves. Should I leave it be and fill with epoxy filler after lamination? Any general suggestions or comments about Vaccum Infusion would be greatly appreciated.

Thanks,

Salmonid

9608

9609

[MarshallT]

Looking at the photo I would guess that this foam core is not meant to be used for vacuum infusion. The grooves are there so it can be used on curved survaces. A core for vacuum infusion needs to have small holes drilled through the thickness to ensure that resin can flow frfom one side to the other. Otherwise you can runb into a problem where resin does not fill the space under the core ( an area that you cannot see). Also you have to be careful whic way to lay out your flow. If you do it along the lenght the resin will flow fast along the grooves and could end up blocking off the vaccum line before the entire part is filled. It would probably be better to have the flow run along the width.
You do not have to use Enkafusion for such a small part. The spriral tubing covered with peel ply will work. Either way you do not want to lay the resin inlet line (or the vacuum line) directly on the foam core. Take a piece of peel ply and fold it over the inlet line with a small slit on top for the "T" connector. You just have to make sure that the open end of the peel ply which is wrapped around the inlet line comes in direct contact with the fibre to be infused.
Your core needs to be tappered at 45 degrees or so. This should be done for hand layup as well but in the case of infusion the vacuum bag will not seal tight against the mold at the edge of the core which will give a niece channel for resin to flow around the part and block off the vaccum line.

It is a diffucult to explain these things in a short post. You really need to try these things.

Assuming you really want to do it by infusion my suggestion for you would be to do some trial runs on a temp mold such as a sheet of melamine to see how it works. My real suggestion would be to do it by hand lay-up then vacuum bagging to ensure the core is well bonded.