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  #1  
Old 05-31-2016, 09:17 PM
mgregory176 mgregory176 is offline
 
Join Date: May 2011
Location: DE
Posts: 78
Default Fairing delamination

So I was pretty happy with the results of the windscreen fairing until I started seeing the leading edge lifting as I sanded to the recommended thickness so I kept sanding it back hoping that the bond would be better further back.No joy. The bond to the plexiglass seems to be very good. Is there any way to salvage this short of removal and redoing?



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  #2  
Old 05-31-2016, 09:53 PM
Kyle Boatright Kyle Boatright is online now
 
Join Date: Aug 2005
Location: Atlanta, GA
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A couple of solutions come to mind.

1) Pop it all the way off, then re-glue it. Add in a couple of pop rivets if it makes you feel better.

2) Visit your local farm supply store and buy yourself some syringes. Fill said syringes with epoxy and maybe some cabosil and inject under the delaminated areas. BTW, your fiberglass layup looks very dry to me.
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  #3  
Old 06-01-2016, 11:03 PM
drone_pilot drone_pilot is offline
 
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Location: Hobbs, NM
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I feel your pain. I just did my Tip Up fairing. Spent a week and a half sanding and filling to perfection. Really proud of the turn out. Purchased the high build primer. Decided I'd cleco the front skin in place to check the fit. Looked good to me. Went to open the canopy, snagged the skirt on the forward skin and it popped my epoxy bond on the front edge of the fairing. Anyway, I've been toying with the idea of grinding the front edge back and laying another ply of fiberglass.

I haven't started yet but I think I'm going to inject straight epoxy under the edge. It appears to be pulled off 1/4" at the very most but only in one small spot. I'm then going to layup one more ply about 1/8" below the canopy line and extend it forward of the existing forward edge about 1/4". It shouldn't take much micro to blend and make it as good as new.

This thing looks like an airplane, had my first engine start last week, and feel like I'm a million miles from finishing when setbacks like that happen! Oh well, perseverance builds character! Keep on truckin!
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Last edited by rv6rick : 06-02-2016 at 04:22 AM. Reason: Removed expletives
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  #4  
Old 06-02-2016, 11:39 PM
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whittfic whittfic is offline
 
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West systems epoxy resin will not adhere well to bare aluminium (or acrylic for that matter), it needs a primer of some sort to make it work. There are various ways of achieving a good bond but the easiest way is to paint the bare metal with epoxy primer. It also must be scrupulously clean with all contaminants removed. Don't even wipe it with your bare hand.

Another trick is to 'paint' some epoxy glue such as Araldite or similar onto the bare metal and then do the laminate on top of that. In your case you may be able to extrude some of this under the laminate to bond it down. Don't know how successful you will be with this but it might be worth an experiment.

Good luck,

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Auckland
New Zealand
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  #5  
Old 06-03-2016, 05:57 AM
BillL BillL is offline
 
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Suggest you call West Systems technical help line, give the guy all the material details and prep process. The tech guys I have spoken to seem very knowledgeable. A friend said they recommended G-Flex for better adherence to the plexiglass, with a flame pretreatment. He did peel testing and confirmed it was much better. I am waiting until the forward skin is riveted to do my glass and purchased the g-flex for this purpose. Please don't take this as gospel, check for yourself. Aluminum was very good from their testing, odd. If it is poor prep, then injecting something under to fix it seems . . . questionable.

http://www.westsystem.com/ss/g-flex-epoxy/

This is not to say Vans method is faulty, it seems to server the purpose very well. But - with the lower peel strength (plexi) it might be sensitive to preparation process. Good mechanical prep, no dust and no oils. The g-flex was suggested here as a repair option.

Clive, any particular Araldite product? It seems they make a wide range of adhesives.
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Last edited by BillL : 06-03-2016 at 06:09 AM.
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  #6  
Old 06-03-2016, 06:04 AM
BillL BillL is offline
 
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Quote:
Originally Posted by drone_pilot View Post

it looks like an airplane but. . .feel like I'm a million miles from finishing when setbacks like that happen! fiberglassing . . . expletives deleted . . . !
Amen Brother!!
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  #7  
Old 06-03-2016, 10:24 PM
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whittfic whittfic is offline
 
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The Araldite I was suggesting is the typical epoxy glue product that can be found in the local hardware store (see photo) http://rs456.pbsrc.com/albums/qq282/...0?t=1464923425

I used an earlier version of this to repair the damaged cast aluminium fuel tank on my Dad's chainsaw back in the mid 1970's. Forty or so years later and it has never come off or leaked. (Chainsaw still works too! See other photo) http://i456.photobucket.com/albums/q...g?t=1464923297

There are many types of epoxy resins and glues, all with various properties and formulations depending on the application required. The chemistry behind it all is witchcraft to me but have learnt the hard way that for a reliable bond the West System resin does need a suitable etch primer to make it stick to aluminium no matter how well it is cleaned and scuffed.

The glue suggestion was something that could be tried in the absence of a supply of primer. It also might be worth trying in the original posters situation is he wants to try and save the laminate he has already done. Prudence suggests trying it on a test lay-up on a spare piece of aluminium first. Peel the lay-up off and try glueing it back down. If it doesn't work to his satisfaction there is little option other than to start over.

Clive Whittfield
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  #8  
Old 06-05-2016, 08:52 PM
sf3543 sf3543 is offline
 
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Looking at the exposed aluminum below where the lamination is exposed, it looks like the surface has not been roughed up enough to get a good bond.
You need to aggressively rough up that area with some 80 or 60 grit Emory cloth or sand paper. Leave as many deep scratches as possible for the epoxy to get a grip. The same with the plexiglass.
If it is truly bonded well to the plexiglass, you could cut away the parts not bonded and just re glass it, same as you would a repair, using either glass cloth or flox
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  #9  
Old 06-06-2016, 10:37 AM
edbooth edbooth is offline
 
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I'm with Kyle B., from the pix , looks like the cloth was not wetted out completely. I would redo the whole thing.....any job worth doing is worth doing well.
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  #10  
Old 06-06-2016, 01:21 PM
Lars Lars is offline
 
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As mentioned, epoxy to metal (and to plastic) bonds can be improved with primers. Since I had some Sika primer left over from my Sikaflex canopy bonding, I decided to test it. I made up some test coupons with strips of fiberglass laminated to scrap pieces of canopy acrylic and aluminum sheet, using West Systems epoxy. The bond to aluminum and acrylic that was prepped with Sika primer was tenacious; the fiberglass strips bonded to unprimed substrates peeled off easily. Is the Sika primer optimal? Likely not. It's also expensive if you don't have some already, but there are other choices. I wound up priming both windshield and aluminum skin with the Sika primer when I installed the windshield 4 years ago just before I flew it. I didn't get around to painting the airplane until last Fall, so I inspected the bond regularly (just because I was confident didn't mean I was certain- that was my official answer to the endless "when are you going to paint it?" questions). Still holding up.

As an aside, I used a layer of carbon cloth over the top; you can hang from the roll bar strip and it doesn't bend or delaminate from the windshield.
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