Carbon Testing Part 2! Hollow Molded Monster! - Page 127 - RC Groups
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Jan 19, 2010, 08:15 PM
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Originally Posted by rothlisburger

When you do your live hinges, do you let the epoxy impregnate the kevlar, and then just work the hinge to get it moving, or do you impregnate it with something else to keep the epoxy out?


The kevlar is wetout with epoxy and laminated within the skin layup. I keep my hinge so there is only one layer of carbon over it on the inside of the wing. That helps me free it up with some light sanding once I open up the part.
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Jan 19, 2010, 08:25 PM
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Next I start to pry open the control surface but I do not force it much. I use a stirstick with sandpaper on one edge and sand the carbon as Im prying it open. It starts to open more and more with more sanding until it is open all the way 90 degrees and it is easy to sand only on the hingeline as it becomes a highpoint. Here it is with all the dust blown out of it. This is ready for the wiper.
Jan 19, 2010, 08:28 PM
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Just making sure that I have a full range of motion and nothing is binding. I also check inside where the wiper will go to be sure there are no obstructions like excess epoxy. If so, I use a dremel and clear it out. Once this is all finished it is time to clean away all dust so it doesnt end up in the pretty wiper surface.
Jan 19, 2010, 08:31 PM
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Then I take some two sided tape and place it on the control surface. It needs to be exactly flush in front where the wiper starts so I found it easiest to let it hang over the front and use a razor to trim it flush. Then I trim the ends flush with the ends of the elevator and peel up the scrap.
Jan 19, 2010, 08:51 PM
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Then I cut some clear .005 mylar. I use about a 1.5" strip and stick it to the two sided tape leaving about 3/4" hanging forward. This is about 1/8" longer than my finished wiper will be. I trim the ends flush with the ends of the elevator. This can now be test fit and you can see how the wiper will shape up. If there are any interference issues this is when I will find out and I can either trim the mylar a bit shorter or dremel some more. If I had to dremel more which I always make sure I never have to at this point, I would have to start over by cleaning up all the dust again and retape.
Jan 19, 2010, 08:57 PM
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Now that everything looks good I tape the surface open all the way and stand it up so I can access the inside of the mylar.
Jan 19, 2010, 09:02 PM
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Next I mix up some MGS and microballoons. I think black wipers are the coolest so I added some pigment. Then put it all into a big ziploc.
Jan 19, 2010, 09:08 PM
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Next I put a thick bead right in the corner where the mylar meets the elevator.
Jan 19, 2010, 09:16 PM
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Using a swirling action and a small wooden stick I make a pass from one end to the other working the mixture up onto the inside of the elevator and the torque tube inside. Then, I make another pass right in the corner where the tape meets the elevator to clear any bubbles that might be stuck in the mix.
Jan 19, 2010, 09:19 PM
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Now it's time to take a look at how they are coming along by looking at the outside of the mylar. Im looking for any voids and making sure that there are no bubbles stuck down in the corner.
Jan 19, 2010, 09:21 PM
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Here you can see some tiny bubbles that need to be filled. A little loving with the wooden stick and they disappear.
Jan 19, 2010, 09:23 PM
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All gone.
Jan 19, 2010, 09:28 PM
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Next I put another heavy bead across basically right in the front edge of where I want the wiper to end and smooth it out so it's a constant thickness all the way across adding more in shallow areas if needed. I use the stick to push the mix right up to the edges at the ends of the elevator. If the mix is too thin it will run into the cracks. Too thick and you cant get all the bubbles out.
Jan 19, 2010, 09:35 PM
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Now I make one final inspection of the back of the mylar and then tuck the front edge of the mylar up under the skin of the stab. I had to untape the elevator to get it to close a bit and once it's tucked all the way in I retape the elevator in a position representing my max throw or slightly more.
Jan 19, 2010, 09:36 PM
Stay in it!!!!
All tucked in and a quick wipe with lacquer thinner if I left any mess and time to turn it over to cure.

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