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Fiber Fuse: Ply Formers

Old 05-04-2016, 05:46 PM
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Default Fiber Fuse: Ply Formers

What epoxy do I use to attach Ply and balsa formers inside of my Taylor P-51 fiber fuse? Can I use Z-Poxy finish resin with some 2 oz cloth? I'm fairly confident the fuse is epoxy glass (from B Holman) and not Polyester. BTW how do you tell the difference?

Thanx, Mark
Old 05-04-2016, 07:28 PM
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Sand the inside of the fuse were you want to glue something and you can tell by the smell if it's polyester resin or an epoxy resin.

As far as what type of glue to use. Todays best glue for attaching formers into fuselages is the Hysol glues that are a 2 part aerospace type of glue.
Old 05-05-2016, 04:43 AM
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What kind of smell does it produce?

Mark
Old 05-05-2016, 05:30 AM
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Originally Posted by mark IX
What kind of smell does it produce?

Mark
Polyester will have a very strong almost sweet smell to it.

A picture of the fuse would help to try and give you a clue.
Old 05-05-2016, 05:34 AM
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If it's a dark yellow to almost brown color then it is more than likely an Epoxy resin.

If it's green in color then it is more than likely Polyester.
Old 05-05-2016, 06:08 AM
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Do NOT use finishing resin. It's not made for strength. Either use 30 min. Epoxy or hysol.
Old 05-05-2016, 07:05 AM
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I use Hysol 9462 on all my glass fuses both epoxy and poly resin type . It costs more but it bonds very well , stays where you put , doesn't run and has better shock resistance than epoxy or poly resin.
BVM sells Aeropoxy that is similar to if not the same as.
I get mine from Dreamworks or whoever has it cheapest on the interweb.
Old 05-05-2016, 07:11 AM
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The fuse is definitely brown in color. Any particular brand of 30 min Epoxy?
Old 05-05-2016, 08:27 AM
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No particular brand necessary. Any 30 min will work.
Old 05-12-2016, 08:56 AM
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When it comes to composites if you ask 10 qualified composites guys how to do something you will get 12 answers. For the most part all 12 would work. I have installed formers in a glass fuse using a couple methods. I have tacked them in place with CA and then mixed up a slurry of laminating resin and milled fiber. Using a paper cone to apply a bead much like a cake decorator all around the joint and then smoothing with a gloved finger. For additional strength, I have again tacked the former in place with CA and then went along the joint with some 20K CF tow to form a radius followed by a layer of 2-3.7 oz cloth. That is the method I used to attach the gear plate into my 40 lb Extra 330. More important will be the surface prep, I suggest an acetone wipe, 15 minute flash, sand with 220, dry wipe to remove dust, acetone wipe, bond within 2 hours.
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Old 05-13-2016, 09:04 AM
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When I built my Vailiancourt P-47 years ago the plans said to use automotive polyester resin(Bonco) . I rough up the surface of the fuse, drilled some holes around the perimeter of the former about 1" apart. Tacked them it with CA and than made a fillet of bondo with my finger with a latex glove. It was cheap, fast and very clean. Never had a problem with them. Just a little messier to do than with Hysol and the glue tips that comes with it. But on a larger fuse the bondo method is easy.
My 2 cents
Old 05-13-2016, 10:17 AM
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Polyester resin and Bondo is not the same thing although Bondo is polyester based. For that to have worked at all your fuselage had to have been made out of polyester in the first place. The Bondo has poor strength charictaristics and is heavy. IMO that method would have been at the very bottom of my list.

As a side note, this may be a bit harsh but IMO any of the hobby packaged expoxies that are a 1:1 mix are junk. We tend to overbuild our models so in most cases it's not an issue however if you are looking for the strongest bond with minimum weight gain then the CF tow fillet with light cloth overlay using laminating resin would be my first choice, second choice is a slurry of laminating resin with milled fiber and Cabosil added to make a paste adhesive. As stated previously the prep is a huge factor in success or failure in whichever method/products you use, unless using a polyester based product on a epoxy based fuselage. That is destined to fail no matter what prep is done.

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Old 05-22-2016, 04:21 PM
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Thx guys. I'll go with the 30 min epoxy method.

Mark

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