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Old Nov 15, 2010, 08:32 PM
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St.Catharines, Ontario
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deffinitely go with FG Phil. not only is it the best option to colour match (paint), but it'll give the best ding resistant finish, for all those minor hangar rash issues that we all suffer from time to time. if you cover it with film and you ding it, it's gonna show and be more difficult to repair/patch. FG is remarkably easy to repair if you damage it. as Julian said, FG doesn't add that much weight, if you do it well enough............a layer of 2oz cloth might be all you need to cover the entire plane and give a great finish. if you use peel ply, you can get a smooth finish that you can scrape with a razor blade to get any imperfections out and then a light sand for your primer coat. if you don't use peel ply, you can still scrape with a razor blade first, but it'll require a little extra elbow grease to get it smooth. peel ply isn't a must, but it's a great benefit, as it will provide you with the best means of getting the best coverage with the least amount of resin. and don't forget to use epoxy resin, not polyester resin. polyester shrinks, where epoxy doesn't.

Rich
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Old Nov 16, 2010, 03:43 AM
smithy
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Cornwall, UK
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Right then fibreglass it is, only trouble is winter's setting in and its only getting up to 48 degs at the moment so i'll have to sweet talk 'her indoors' to let me take over the kitchen table when im ready. Was hoping to get away with doing it outside. Btw, what is the ideal temp for epoxy resin to cure? Thanks for the tips Rich, no doubt i'll be racking your brain when i start to do it, soon hopefully, what is peel ply btw?

Cheers
Phil
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Old Nov 16, 2010, 01:15 PM
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peel ply is a film that is placed over the FG once it's been saturated with resin. then you simply squeegie out the resin with a credit card (or similar) and let it cure completely. once it's cured, you peel off the film and you are left with an almost completely smooth outer surface, which you can then scrape off with a razor blade to remove imperfections and then lightly sand for painting.

all is not lost when you have cold weather to deal with. you have some solutions to cope with this problem. first is a space heater for your work space. they can get expensive on your electricity bill though, if they are electric. gas is much better. you can also work inside, if you don't mind putting up with a nagging wife. OR, you can build a hot box. a hot box can be made as big or small as you like and is really simple to build. you can make it out of wood, bricks, or any building material you can find. the point of it, would be to build a box structure, large enough to put your wings in it and also your fuselage................seperately of course. LOL. my hot box is made out of 3/4 inch ply and lined with aluminium foil, shiny side out. the aluminium foil is necessary to keep the heat focused in the box. the wood or brick is your insulator. my box is 4 feet long by 2 feet wide and the lid is a simple piece of 2 inch insulation foam, lined with aluminium foil. the heat source in my box is four 100 Watt light bulbs, spaced evenly along the length of the box. they are held in place on the wall of the box, near the lid. here's how to use the box properly....................

keep your epoxy, cloth, plane in the house for several days before you glass. this will bring everything up to room temp, which is the ideal temp for your resin anyway. a few hours before you glass, turn on the hot box, so it can bring up the internal temp of the box. just before you glass, put some wax paper on the bottom of the hot box, to stop any resin leakage destroying your foil. set up your work bench to allow faster work progress. I would pre-cut your cloth in sections, to fit the plane, before you mix any resin. this way, you'll know where you are and where those pieces go. work in small sections at a time, mixing only as much resin as is needed for that section. the smaller the batch, the longer the set up time will be. remember, that you don't have to glass the whole thing at once, but you can if you want to. that's up to you completely. if it were me, I would try and glass the whole thing at once and put it in the hot box. you can also use denatured alcohol to thin out the resin a bit, but I wouldn't go any more than 25% mix ratio. I know guys that use 50% ratio, but the problem is, is that epoxy gets more brittle as you use more alcohol. 25% ratio will cause no problems though. this will extend your work time and allow better coverage of the resin, especially if you don't use peel ply. you'll be able to use the epoxy out in your workspace, after it's heated up to room temp. I wouldn't leave it outside for more than an hour or two, as the resin temp will come down and won't mix the same after that. I might be tempted to mix the resin indoors and then quickly work outside. you'll figure it out though. LOL.
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Old Nov 17, 2010, 02:33 AM
smithy
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Cornwall, UK
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Wow, thanks Rich. Hot box sounds like a really simple but good idea. Another question, when i start glassing the wings, for example, would i have to wait for the top half to cure first before glassing the bottom half. I have found a couple of suppliers that have peel ply, one comes in 1mtr widths and the other in 100mm widths. Which do you think would be best? Also ( sorry for the questions, did say i would pick your brain!!) would 49gsm cloth be too light?

Cheers

Phil
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Old Nov 17, 2010, 06:44 PM
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good question.................I have no idea, cause I buy in oz, not grams. do the math for me Phil, cause I'm lazy. LOL.

you can glass all at once, or do it in sections, such as wing top, then wing bottom. it's totally up to you and is six of one, half a dozen of the other. I would tend to say to work in smaller areas at a time, as it will cause you less grief and less chance of a screw up. if you feel rushed to do too much at a time, mistakes can be made. here's how I would attack a wing...................do the bottom first, then the top, but don't do the leading edge. do the LE last, as you'll be able to wrap it over the top of both sides of the cured wing skins. then just sand it smooth. OR, you can do all at once. start from the trainling edge of the bottom side of the wing. wrap it over to the top side of the wing and continue all the way over the leading edge and back along the bottom of the wing to the trailing edge. put your peel ply on and squeegie out the excess resin. if you feel comfortable enough to do it this way, it's probably the better of the two options. you could always find an old wing, or make a new wing out of foam or something and practice doing it this way, to see how you do.

here's another way to do it without peel ply..................simply cut out all your cloth to the correct shapes, so you can lay it all up at the same time. mix your resin up using 25% alcohol and take your cloth section by section and wet it out on the piece you are working on. use a stiff brush to wet it out if you like, but once it's wetted out, you can use a credit card to squeegie it out. squeegie it out till you get almost no pooling of the resin from the edges of your credit card. that's good enough to allow it to cure. once you've let it cure, say over 24 hours, you'll be ready to prep it. it takes a bit of extra work, but it's easy enough to do. first thing is to scrape the surface with a razor blade. just drag it over the surface and you'll see the material coming off in a powder-like substance. once you've scraped it all off, you can give it a light sand with 240 grit, then 300. see what you've got at that point. if it looks smooth, take it to 400 grit. if you can't get it completely smooth, get some primer in a can, put some in a mixing cup and thin it out so it's a bit runnier. then simply apply it liberally with a credit card and allow to dry. this should fill in smaller pin holes. if you've got major blemishes, you'll have to use a high solid primer. spray it on and let dry, then sand, then repeat till you've built up the surface and removed all blemishes. like I said, it's a bit more time consuming than the peel ply method and arguably, it'll be slightly heavier too. remember that if you do it the spray primer way, only spray as much as you need to cover it. this will keep the weight down. same goes for your paint layers........only spray as much as you need to get complete coverage. anything else is just plain overkill and added weight you don't need. this is where an airbrush comes in handy. by the way, my brain is always available to be picked at. LOL.
Rich
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Old Nov 18, 2010, 12:53 AM
smithy
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Cornwall, UK
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There's a company here called Fibretech that do finishing kits, cloth resin and tools in one kit. Dont know wether to go for the 49 gms (1.7 oz) or the 25 gsm kit (0.8 oz), or would i need a heavier cloth.

Phil
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Old Nov 18, 2010, 06:39 PM
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well, the 1.7 oz goes right along with my recommendation of 2 oz cloth. I think the .8 oz is a little light for your application, which is why I would pick the heavier of those two. I would choose between 25 gram to 49 gram, but no less than 25. the weave will be very small on the lighter cloth and may not conform to all curves, which may induce some lifting problems. for this reason, sometimes a heavier cloth with the weave placed on a 45 degree angle, can follow the contours better. with your model, you can afford to have a bit of extra weight with the use of heavier cloth. PM Air Sally (Rodger), or perhaps Dan Savage and ask them what they think. I have experience with composites, but they are the guru's with composites at this size.
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Old Nov 19, 2010, 01:25 PM
smithy
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Thanks Rich. I think i'll go with the 49gsm.

Phil
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Old Nov 19, 2010, 09:59 PM
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also check out this link. there's some very good information on this thread and well worth a read before you buy anything.

http://www.rcgroups.com/forums/showthread.php?t=1323067
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Old Nov 21, 2010, 04:18 PM
Will fly for food
Maryland
Joined Sep 2004
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When I glass, I apply fabric, epoxy. Then gently heat with heat gun or hair dryer, and blot with paper towels. The heat things the epoxy, and the paper towels remove the excess resin.

Quick and easy.
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Old Nov 21, 2010, 07:17 PM
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that's a great method for curing the epoxy faster in cold conditions. there is one drawback worth pointing out with that method though.............if you do this, you can't control the amount of heat and where it's applied. by that, I mean that once you've moved over one area and on to the next, that spot rapidly decreases in temperature, while the next spot heats up. because of this, you get uneven curing, which can lead to brittleness and/or failure of a part.

I do like the method mentioned by Pinecone, but as in any method, there are always drawbacks and that is one of them. if I were galssing a small piece, such as a hatch, I would say to use that method, as it's less critical. for an entire fuselage/wings, you can't beat a hot box, or the preferred method, which is heating the whole room. of course, if you can talk your better half into getting high off resin fumes, you could always use the house and not have to worry about anything at all. LOL.

perhaps an unused room in the house with some good ventilation to the outside?????? LOL.
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Old Dec 07, 2010, 03:46 AM
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white lake michigan
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I like .75 or 3/4oz cloth for my models. It is just about right and easy to work with. I have draped it over the whole top of a model and did the top and sides and flipped it over and finished the whole fuse in one piece it conforms very good to compound curves. But with yours having the stabs and fin glued on I would do it in sections.
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Old Dec 07, 2010, 07:13 AM
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you could also coat the whole plane with dope, before you FG it. this will seal in the wood, without adding weight and will allow you to use less resin, because none will soak into the balsa underneath the cloth. just a thought.
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Old Jan 03, 2011, 12:21 PM
smithy
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Cornwall, UK
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Its been a while i know, new years resolution: must build faster!!

The wing is just about done and ready for glassing. Made the wing tips/ 'airbrakes' ( non functional ) and made up a couple of tubes out of rolled photo card for the wing bolts to fit into.

Phil
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Old Jan 03, 2011, 05:02 PM
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lookin' good Phil.
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