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Building Tips and technical articles. => Building techniques => Topic started by: Motorman on December 17, 2015, 12:45:35 PM
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The plane I'm building has 1/2x3/8 trailing edge on the stab then .010" CF laminate then 1/2x1/8 cap on the back. Using DuBro hinges. How do you get the hinge slot through the laminate? I have one of those Christmas tree slot cutters that works great for balsa but will it punch through the CF?
Thanks,
MM
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Just about any material that involves fibers in a matrix (wood, fiberglass, CF, etc.) dulls blades quickly. CF is particularly bad because the fibers are so strong.
I wouldn't use any blade on CF that I couldn't either toss or hand-sharpen. In your case, I think I'd rough-cut the CF with an xActo #11 blade or a Dremel Dangerous Disk, then finish the slot "correctly" with the slotting tool.
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.010 is pretty thin. I'd just use a #11 to slit the CF then back with the slotting tool. Let us know how you decide to do it and how well it works out, MM.
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It seems like a waste to put a strip of CF vertically on the stabilizer TE. I'd put thinner stuff on the top and bottom, where it should do more good.
If you want to avoid cutting slots in the CF strip and leave it vertical, you might split it full length, and leave a gap for the hinge tabs. OBTW, since epoxy doesn't stick well to epoxy, the approved method is to glue CF strips on with CA, not epoxy. D>K Steve
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That's funny somebody else told me they glue laminate to balsa with epoxy now I've got four 27" lengths of spar I'm wondering about.
MM
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That's funny somebody else told me they glue laminate to balsa with epoxy now I've got four 27" lengths of spar I'm wondering about.
They'll be fine.
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Did a test with .010" Dave brown CF laminate between two strips of 1/8th balsa with CA glue. The hinge slotting tool punched right through it no problem.
I also wanted to see if the CA would stick to the CF and it did very well. The problem was the glue didn't get to all areas of the joint. It was 1/2" strips lightly clamped together and I used thin CA on the edges. I was thinking of making some little cross cuts in the balsa with a #11 to give the glue channels to the center.
MM
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I don't use CA on a hinge. Well, unless it was a CA hinge.
I've used the Du-bro type hinges, Klett actually, on many models, including the pattern ships I built years ago.
Up to and including the CL models I've built recently.
Here's what we did, or how I was taught to install a hinge.
We would make a cut in the center from the back towards the pivot pin, about 3/4 of the way towards the pin.
If you try this on a hinge you will see that it creates a side that is high and a side that is low.
This would allow for a tighter fit when installed. I use 20 minute Epoxy but I'm up for better suggestions.
Keep in mind, I attach my control surfaces before I paint. I also toothpick pin the end hinge.
That's the way I was taught.
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Can't picture what you're talking about. I use epoxy on hinges too.
Anyway, I tried the CA with the cuts in the balsa and it still didn't penetrate to the center. I guess it dries too fast. Went ahead and used epoxy to glue the laminate/balsa sandwich.
MM
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Fellows, I am one of the very few that does not glue pinned hinges. I have done it in the past in various ways and found it much easier and less messy to just put the hinges in place, drill the holes and use tooth picks or the bamboo skewers. A drop of CA to the end of the tooth pick or skewer. Then sand.
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LOL, Just wanted someone to see this before I sheet it over. Those little black lines are the CF. Way too much work there has to be an easier way.
(http://i889.photobucket.com/albums/ac93/giffy6/Thunder%20Gazer%20Stab.jpg) (http://s889.photobucket.com/user/giffy6/media/Thunder%20Gazer%20Stab.jpg.html)
MM
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very tidy,
my two cents worth, I think your carbon would have been more productive on the top and bottom of the read spar , I am not sure how much strength it will actually contribute in the configureation you have it in,,
Howard could speak more directly with numbers,, but my understanding of the situation is, the carbon needs to be so it resists the bending which would be the tips moving vertically with respect to the center section,
that said, Very neat building job
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I like the way the hinges are anchored into the carbon fiber.
MM
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I got the sheeting on one side with CA glue and it dawned on me there's no access to glue the ribs ect. for the other side on the sheeting. Do you think I can get medium CA on all those ribs and slap the planking down before it dries?
MM