A.A. Barry Posted February 26, 2015 Share Posted February 26, 2015 Hi all, I need a little help here with building F/Glass cowls for my pet areoplane Ok they say that the West System epoxy is the stuff to use, but what weight/ thickness and do I use "chopped"or a matt??? The cowl will be created on the model over polyurathane foam, which when set will be removed and the inside foam removed, leaving just a shell Any ideas guys Barry Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 26, 2015 Share Posted February 26, 2015 Never done one Barry so i'm not much help, but a quick google shows videos/tutorials on how to do them. John Quote Link to comment Share on other sites More sharing options...
Matt Jones Posted February 26, 2015 Share Posted February 26, 2015 Everyone will have a different view, personally I'd go 160-200g/sq metre in weight and twill weave (drapes much better around compound curves than plain weave). Also, although it says that resin cures in 24 hours make sure you leave it in an airing cupboard for 48 hours minimum, the resin is still very 'green' after only 1 day. This means it's still soft and may lose some of it's shape. Stay away from chopped strand mat!!! Quote Link to comment Share on other sites More sharing options...
A.A. Barry Posted February 26, 2015 Author Share Posted February 26, 2015 That's great Matt, any idea where I can obtain some?? Quote Link to comment Share on other sites More sharing options...
A.A. Barry Posted February 26, 2015 Author Share Posted February 26, 2015 Matt, is twill weave the same as woven cloth?? Barry Quote Link to comment Share on other sites More sharing options...
Matt Jones Posted February 26, 2015 Share Posted February 26, 2015 Try Google..... Quote Link to comment Share on other sites More sharing options...
Colin Bernard Posted February 26, 2015 Share Posted February 26, 2015 You may find this link useful here which suggests 160g/sq metre It's on Bucks Composites website. I have always found them very helpful and they are at most of the shows each year. Quote Link to comment Share on other sites More sharing options...
olav sivertsen 1 Posted February 26, 2015 Share Posted February 26, 2015 having made many different type of cowl,I use the following method, Gel coat your mould ,having applied several layers of release wax first. Cut out several panels of fibreglass tissue to cover the inside of your mould, so that when laying up you overlap each panel slightly. Fibreglass matting is made up of two to three layers of chop strand on top of each other.You can carefully separate these layers into panels as you did for the fibre glass tissue .Lay up these panels as you did with the tissue going around the mould at least twice and make sure that the fibres are well wetted out. You will end up with a very thin flexible cowling which will become sufficiently rigid once the glass is cured. I always use Polyester resin and the reason I use tissue for the first layer is that if your gel coat is a bit thin in places,when you rub down your completed cowl down for priming and painting,if you go through the gel coat you won,'t end up with the matt cloth showing through.Hope this is of some help to anyone contemplating having ago at making fibre glass mouldings.Very satisfying.If anyone requires any help drop me an e-mail. Quote Link to comment Share on other sites More sharing options...
Andy48 Posted February 26, 2015 Share Posted February 26, 2015 I made a cowl out of balsa sealed with sanding sealer. Then I used plaster of paris to make a mould. Both the cowl and the mould were waxed to prevent sticking. I simply used standard motor repair fibreglass resin with the fine non-woven fibreglass to build up the cowl one layer at a time. Two layers of fibreglass makes a lightweight cowl. More layers would make a stronger cowl, and it can be reinforced where needed. Then I cleaned off any residual wax and sprayed it with primer to show up any pinholes and blemishes. In the end, the finish was super. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted February 26, 2015 Share Posted February 26, 2015 These fine chaps will sort you out.....definitely go for a woven cloth over chopped strand mat...much lighter & stronger... Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 3, 2015 Share Posted April 3, 2015 Hi I thought these pics might show the stages of making a cowling. I used polyester resin without the accelerator added, this gives plenty of working time .If you use the Davids resin from car accessory shops it will set much faster .Polyeste is fine for cowlings and cheaper than epoxy .It cures quicker but dont rush it,let it set fully before trying to remove from mold . I used an old wooden cowl as a plug to make a mold for my Luscombe Silvaire . The mode was bought from Avicraft , secondhand and hadn't been finished . As far as I'm aware it's a home build so no glass parts available . The wooden cowl was a bit rubbish so some filler and sanding later it was a smooth plug .This was given many coats of release wax polished between coats and allowed to harden .Using polyester resin the mold was made by coating the plug with gel coat and allow to start to set then laminating chopped glass over that with normal resin . some stiffener plates from old ply was glassed onto the mold. When fully cured the plug was removed. this came out pretty clean . Any small marks in the mold were filled and the the mold was given lots of coats of release wax . The mold was given a coat of gel coat which was allowed to part cure before glass clothe was laid up inside . The edges where mounting screws were to be used were given some extra glass reinforcement. Getting the cowl out of the mold was difficult considering it is a simple shape. The next time i do this I will spray the mold with PVA release agent Edited By Engine Doctor on 03/04/2015 11:18:57 Edited By Engine Doctor on 03/04/2015 11:19:33 Edited By Engine Doctor on 03/04/2015 11:32:15 Quote Link to comment Share on other sites More sharing options...
Dane Crosby Posted April 3, 2015 Share Posted April 3, 2015 Andy. Exactly how I make them! I waxed the mold but also painted on the blue release agent to the waxed mold. Belt and braces really. If there are compound curves I find I can get away with a thin fibreglass layer. It is strong when fully cured. Quote Link to comment Share on other sites More sharing options...
Danny M2Z Posted April 3, 2015 Share Posted April 3, 2015 A tip from the gunsmiths who use epoxy bedding for rifle barrels. Kiwi neutral boot polish is a really good release agent and it's cheap. * Danny M * Quote Link to comment Share on other sites More sharing options...
Ernie Posted April 3, 2015 Share Posted April 3, 2015 Hi Barry I use a similar technique fior making all sorts of bits and pieces. I use blue foam, It sands much easier, and will take more detail. Give your 'male ' mould a couple of coats of emulsion to protect the foam from the resin. Use the lightest glass cloth you can find, and build up several layers. You can thus make it thicker for fixing points etc. Finally, use acetone to get rid od the foam ernie Quote Link to comment Share on other sites More sharing options...
A.A. Barry Posted April 3, 2015 Author Share Posted April 3, 2015 Thx guys for all the input, I can least get a better result now Barry Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 4, 2015 Share Posted April 4, 2015 Posted by Danny M2Z on 03/04/2015 11:45:07: A tip from the gunsmiths who use epoxy bedding for rifle barrels. Kiwi neutral boot polish is a really good release agent and it's cheap. * Danny M * Thanks for the tip .I'll try that the next time Quote Link to comment Share on other sites More sharing options...
A.A. Barry Posted April 4, 2015 Author Share Posted April 4, 2015 I bought some today. Thanks Barry Edited By A.A. Barry on 04/04/2015 10:50:52 Quote Link to comment Share on other sites More sharing options...
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