By Fredrik Welen - 12/9/2017 10:04:29 PM
Hi.. I am pretty new to this and I need guidance and help walking me through this process..
I have done some wet layups but never infusion parts and I know I am taking a chance making a big part like this the first time.. But I need to learn the process for future parts too and hopefuly with help from this forum I will make it.. I might be able to try some small stuff first though. Rear side panels maybe.
The car is a -91 Honda civic hatch that I have been working on now and then for over 15 years and will be something of a time attack/street car. The roof is about 1,5mx1m in size. I have made a mold of the stock roof and after that the car has been painted without a roof. The skeleton structure that the stock roof sheet are glued to are left on the car.
I made a nice wet layup in my mold of 2 layers of 200g twill. I used peel ply, perforated release film and breather and with vacuum to that the part came out pretty nice but way to thin.. I put the part back in the mold and added 2 more layers of 200g and pulled vacuum again and it was a big fail.. The surface was not straight at all and it was deformed.. I then got tired of it and took my polyester mold to a professional that would make a part for me using my mold with a autoclave and pre preg. I told those guys that they need to make sure the mold can take the heat and pressures.. I had no Idea if it could handle it.. They said they would be careful and try it in the autoclave before laying up the part.. It was a disaster.. I should have known but I trusted them.. Every little small air bubble were pulled through several layers of 600g fiberglass and gel coat. I later discovered it was slightly deformed too. I was disappointed to say the least.. I just put everything away for almost 2 years before I now began to deal with it again.
So.. Looking at a lot of youtube tutorials and videos it seems that infusion is the way to go.. I am ordering a lot of stuff from easy composites but I need help choosing everything before ordering.. I live in Sweden so I would like to save some shipping cost ordering as few times as I can..
I am debating on fixing the mold or make a new one.. Making a new one involves finding a good roof to make a mold of and get some more chemicals and consumables for it. I might even need to have that roof fixed from dents and painted before making a good mold. It is time consuming and kind of expensive.. I have sanded the old mold straight but all of maybe 100 holes of different size needs to be filled and I was thinking of using regular polyester bodywork filler and then have the mold painted by a professional car body painter. Whats your thoughts on this..
If I am in need of making a new mold I would like to have it done so it can handle a autoclave.. That is about 130 degrees and it needs to be free from air bubbles. I think that is not an easy task when you need a lot of layers for getting the mold to about 5mm thick.. The guys from the shop that destroyed my mold has a epoxy i can use for making the mold that can handle the heat but they don´t have any gel coats. They suggested biresin s8 or sika s8 but it is hard to get a hold of.. Using that doesn´t need a post cure to handle 130 degree ether if I understand correctly. I need to learn to do infusions for other parts and projects so I just might start with this roof anyway.
I will get some pictures up so you guys get a better idea of the contours and the shapes of the mold. There are some 90 degree bends where the drip molding or roof moldings are or whatever they are called in English. Also where the roof meets the wind shield and rear hatch there are a 90 degree edge. I am a bit worried how to get all the layers down enough in all the corners without bridging.. When I did the wet layup I had the tack of the first epoxy layer as help.
I need help thinking this through..
Clear gel coat in the mold or not??.. I want my part to be UV resistant and able to take the sun as any other body part of the car.. Also I want to be able to polish it as the rest of the car using a professional polishing machine. In the beginning I was thinking about to do the infusion without the clear gel coat and then have the finished part clear coated by a professional car painter. But then i saw a tutorial of the makeing of hood using infusion by easy composites and they used the clear gel coat as a first layer in the mold.
The layup then.. I am thinking of 5 layers of 200g CF or maybe 2 layers off 200g and then a part of 300cm x 600cm of soric where the roof hatch used to be and then another 2 layers of 200g over that. I am afraid of the edges of the soric coming throu to the surfice.. Any thought on that? I am avoiding the heavier CF fabrics because of the difficulties getting those around the sharp corners in the mold otherwise I would use a heavier reinforcement.
Also I have some thoughts where to place the feed and vacuum attachments to the layup.. My thoughts was to have infusion mesh over the whole mold and have the feed in the middle center of the mold with some spiral (80-100cm) along the mold centerline. Then the vacuum at the edge with spiral all around the mold.
I am also getting a degassing chamber and catch pot for this.. I rely want a perfect part.
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By Fredrik Welen - 6/24/2018 5:18:17 PM
Got the adhesive.. I taped the edges of the roof and the nearest surface of the car with release tape in case the adhesive swells out of the joints. It will be easier to get rid of the excess adhesive I hope. I also added some blue protective tape so I wont scratch anything hopefully. Then I sanded all the mating suffices with 120 grit and cleaned with acetone. The glue gun for these 200ml "tubes" where kind of expensive but I had some luck and a friend of mine had one at his work he could borrow me.. I could not find them very cheap ether.. about £80 and I don´t think I will use one anytime soon ether.
I also had to make some fab work to get the clamps to work for my rear edge of the roof.. I cut some plywood pieces and placed them along the long sides so I could clamp the roof down.
2 pcs of 200ml packs of the araldite adhesive was enough and I got two extra packs left over to use for something else.. It took me about 20-25 min to get the adhesive on the roof structure and placeing the roof over it and clamp it down.. The adhesive had a pot life of 30 min so I had no time for mistakes. It all went well and now it is just to wait for it to cure..The only thing that could have happened is if I used to little of the adhesive fearing that it would bulge out. I doubt it though. The adhesive worked great but I wish it would have been black instead of the beige color.
I am not sure if I will use new roof seals along the long sides or if I will seal with some black polyurethan sealant just to make sure it is water seald.. Maybe both.. Water has a terrible way of penetrating joints. I just hate to handle that black polyurethane stuff and it has a way of end up everywhere.. I need to figure out how to get nice looking small and even seal..
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