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Old Feb 07, 2013, 07:07 PM
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United States, TX, Houston
Joined May 2003
493 Posts
Help!
Instructions to glass a center section

I bought a ZupAir flying wing and need to join the wing panels using fiberglass and epoxy. Can somebody point me to a pictorial that shows how to do it and get a smooth finish? I can glass it but it would look like crap.
Thanks,
S Gibson
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Old Feb 07, 2013, 07:35 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Where'nthaheck were you Saturday?!?! I missed you!

Lay on the glass, and mix the epoxy. Carefully brush on the epoxy so as not to move the glass. Lay on a paper towel and press it down with a piece of foam padding to absorb the excess. Carefully peal the paper towel off without lifting the glass. Lightly warm the epoxy with a heat gun so the epoxy will flatten. Let it harden and it will be pretty smooth...

See you next trip I make to Houston... or... If you come north, let me know...

Jack
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Old Feb 08, 2013, 07:50 AM
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USA, IL, Naperville
Joined Feb 2003
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Get some 3M Formula 77 at Home depot. Lightly spray the glass then cover it with waxed paper. Trim the glass/paper to size. Lightly spray the glass side of the glass/paper then apply it to the wing. The 77 will hold the glass in place while you remove the paper. Apply the epoxy per the post above.
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Old Feb 08, 2013, 08:53 AM
Fly to live- Live to fly
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My two cents....
http://www.rcgroups.com/forums/showt...1758332&page=5
Manolo.
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Old Feb 08, 2013, 01:13 PM
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Fresno CA
Joined Jul 2006
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Draw a rectangle on a piece of paper the size you want the glass . Tape the paper on work surface on one end. Lay a piece of wax paper over this and tape one end. Lay the glass on the wax paper that is a little larger then the rectangle you drew and tape one end,this holds everything in place while wetting out. Wet out the glass throughly then blot off excess epoxy. Using a rotary cutter or sharp knife cut out the rectangle . lift up the three layers, glass, wax paper and paper. Discard the plain paper. Lay the glass and wax paper on the seem then pull masking tape tightly over the wax paper. After the epoxy has cured, remove the masking tape and wax paper. You should have a nice shiny smooth surface!

I know this sounds like a lot of work, but its really not and the results look very nice. Plus you don't have excess epoxy in places where you don't want it.

I'm opposed to using 3M77 to hold glass in place, it creates a barrier that epoxy cannot penetrate, thus making a weak joint

Blue Skies........................Tim
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Old Feb 08, 2013, 02:15 PM
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United States, CA, Folsom
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Quote:
Originally Posted by RWCLOUD View Post
I'm opposed to using 3M77 to hold glass in place, it creates a barrier that epoxy cannot penetrate, thus making a weak joint

Blue Skies........................Tim
Not when done properly. A quick, light mist is enough to help keep glass in place without affecting the ability of resin to fully wet out the glass and bond to wood or whatever else is underneath.

A heavy soaking coat of 3M77 is a different story and undesirable.

JT
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Old Feb 08, 2013, 03:57 PM
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Quote:
Originally Posted by Hoot View Post
I bought a ZupAir flying wing and need to join the wing panels using fiberglass and epoxy. Can somebody point me to a pictorial that shows how to do it and get a smooth finish? I can glass it but it would look like crap.
Thanks,
S Gibson
You may find this article useful:

http://charlesriverrc.org/articles/c...fiberglass.htm
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Old Feb 08, 2013, 05:44 PM
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United States, TX, Houston
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Thanks for the advice. My problem in the past was the fiberglass fraying on the edges as I brushed on the epoxy.
Jack,
I was in Indiana last weekend. Glad you are back in Texas ! See you this summer !
S Gibson
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Old Feb 08, 2013, 05:52 PM
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United States, CA, San Jose
Joined Mar 2012
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Cut the FG so that the strands are oriented at a 45 (or in an "x" fashion) rather than in a "+" fashion. This way, it won't start unraveling at the edges, and also all of the fibers are working when under load. Otherwise, the fibers running spanwise are doing most of the work.
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Old Feb 08, 2013, 09:20 PM
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Fresno CA
Joined Jul 2006
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Quote:
Originally Posted by Hoot View Post
Thanks for the advice. My problem in the past was the fiberglass fraying on the edges as I brushed on the epoxy.
Jack,
I was in Indiana last weekend. Glad you are back in Texas ! See you this summer !
S Gibson
If you do it my way, you'll have perfectly straight edges, since you don't touch the glass after cutting it. I use 1 layer 0-90 and 1 layer 45 + - 45 of 1.60 ounce glass.

Blue Skies.....................Tim
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Old Feb 08, 2013, 09:56 PM
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I just re-read RWCLOUD's method, as the first time I glossed over it because it was mildly confusing so I merely skipped it. Upon closer reading, his is a superior method.

First benefit: the cutting is easier, as using scissors on "free-floating" fiberglass at a 45 is kinda difficult because the cloth moves all over the place away from the scissors, so cutting out the overall shape AFTER wetting it out, AND while laying flat on worktop, yields a much more uniform cut!!

Second: (could be benefit, could be drawback) with the wax paper, it'll yield a much smoother finish (at the expense of a mild amount of extra epoxy to fill the weave) in one single step.

Third: Most of the messy work is done AWAY from the plane, and then the "final product" is then brought TO the plane.

Perhaps some pics of the process to help those like me who get wrapped up in the wording?
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Old Feb 08, 2013, 10:07 PM
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Fresno CA
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I'm sorry, but I've never taken pictures of the process and I didn't invent it either. Its common in DLG's, so maybe you could find pictures somewhere in the hand launch forum, thats where I learned myself some years ago.

As far as excess weight, once you blot the excess epoxy, there won't be any excess weight even though the top surface is smooth.

If your worried about the wax paper you can use a plastic shopping bag instead. But be for warned, wait until the epoxy is fully cured before removing it, otherwise it might stick forever!But if you wait at least 24 hours, no problem.
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Old Feb 11, 2013, 09:57 PM
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I use the 3M 77 to tack the cloth to the wing. I wet it out and then blot out as much as possible with paper towels. I then use std. 2" clear packing tape and put strips over the wetted cloth and about 1/8" out from the edge of the cloth . I use a rubber roller on top of the tape to squeeze any epoxy to the edge of the tape and sop it up with paper towels. I will work the bottom and then the top side and it takes about 1 hour. After the cure remove the tape and sand the areas that need it and buff with 1200 and your done.
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Old Feb 12, 2013, 08:28 AM
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In the heart of it all.
Joined Feb 2010
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Cutting FG

For those of you who still cut fiber glass in a dry mode, it is a whole bunch easier when you dip your scissors in alcohol just before the cut. Also helps with the pizza style cutter , too. Cutco scissors are the best! Not the cheapest, but the best.
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