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Sep 28, 2019, 10:55 PM
Ken's CAD Models
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Ken
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Oct 03, 2019, 01:26 PM
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I was going to report on the Midwest carbon fiber square tube, which the good people at USPS told me I'd have yesterday. It turned out that by last evening, my tube had just left their Illinois distribution center. So if I see it by Saturday, it'll be a miracle! In the meantime, let me just say a few words (and pix) about Jeff's 3-D printed motor mounts. He includes three different pairs of mounts to fit three different styles of mounting. One of the pairs was almost perfect for my Cobra motors. Just a little tweaking with the power drill made them perfect.
Oct 03, 2019, 06:01 PM
Jer. 29:11
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Glad to hear you were able to adapt the motor mounts.
Oct 06, 2019, 04:28 PM
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I just finished a series of pull tests using scrap MPF and 1" pink foam from the kit and three different kinds of glue: foam-safe ca and kicker, epoxy, and white Gorilla Glue. The last I tested under two conditions: one with pin holes in both pieces plus water, and one without those. Ironically, the Gorilla Glue with pin holes and water was the weakest, although the bond was plenty strong enough for usual flying conditions. There's one thing I've noticed that separates the Gorilla Glue from the rest, and that's the hardened glue. The Gorilla Glue dries foamy, just like Styrofoam, so I'm guessing it will be the easiest to sand, and blend in well on a sanded joint. Anybody else with similar experience, please chime in.
Oct 06, 2019, 05:32 PM
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Here's a heads-up about cleaning Gorilla Glue up with alcohol. Evidently it's a no-no. Just use a clean, dry cloth or something similar.
Oct 06, 2019, 10:11 PM
Jer. 29:11
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Love to learn more about your glue tests.

I have found that Gorilla Glue is fairly difficult to sand well; though it dries hard (versus rubbery), it dries harder than the surrounding foam. So, I typically try to use a very thin layer of glue to minimize the amount that will expand out and need sanding.
Oct 07, 2019, 12:14 AM
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Jeff--Thanks for that one! So that makes all of the glues that I tested about the same when it comes to sanding. In that case, I may use epoxy or foam-safe ca, since neither of those expand. In any case, I'll need a thin layer. And oh, I got my square rod Friday, and tested the difference between it and the round rod, and found that there's no appreciable difference. I plan on using the round rod in combination with a 1/4"-width c. f. strip along the back edge of the top wing piece. Together, I think I'll have the stiffness that I'm looking for.
Oct 07, 2019, 01:52 AM
Danish? Don't U eat that??
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Quote:
Originally Posted by jeffsch
Love to learn more about your glue tests.

I have found that Gorilla Glue is fairly difficult to sand well; though it dries hard (versus rubbery), it dries harder than the surrounding foam. So, I typically try to use a very thin layer of glue to minimize the amount that will expand out and need sanding.
+1 on all accounts (allthough I don't have access to actual GG, only generic brand PU glue - but it behaves exactly the same). In my experience it's actually a lot better to cut the as much as possible of the excess PU glue back with a sharp blade rather than sand it.

I've had quite a bit of luck sandwiching depron layers with PU glue by first applying the glue and spreading it out extremely thin......well, ok....basically I'll scrape almost all of it off again, to be honest, leaving only like a sticky greasy surface, with no actual visible glue. Then i'll mist with a bit of water and wait for it to start foaming(It just builds a very thin foam layer). Then I put the layers together. This way, most of the foaming has already happened when I'm done putting it together, so I can deal with any excess glue foam right away.
Oct 07, 2019, 02:14 AM
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DKChris--Great idea for using PU glue! Thanks!
Oct 08, 2019, 06:46 PM
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Basic Wing Laminations Done


I thought it would be instructive to show you all how I laminated the wing parts using foam-safe ca & kicker and 30-minute epoxy. Using a small paint brush, I applied the kicker right from the open bottle to the spar trough in the bottom piece. Then I applied foam-safe ca in a bead along the bottom of the round c. f. tube spar, pushed it into the trough, and held it with a board for two minutes. I applied 30-minute epoxy to the top piece, making sure I got plenty in the spar trough, and using a scrap "credit card" to squeegee most of the epoxy off the piece. You won't be able to get a fine film of glue on the part like you do with P.U., so what I did in order to keep the top part from sliding off-center to the bottom piece, I pinned the outside and inside edges, and placed a pre-cut board on top in between, weighting it down. As you can see, my building area only allows me to build 1/2 of the wing at a time. I cut off the sides of the rounded interlocking part locators, and slide the one side into the other.
Oct 08, 2019, 10:57 PM
Jer. 29:11
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Nice craftsmanship. And good improvising with the available building area.
Oct 10, 2019, 02:14 PM
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Does anyone know if you can use hot-melt glue on foam without melting the foam? I know I can just try it on a piece of scrap, but I thought I'd let someone with experience chime in. I want to secure my servos with a couple drops of it.
Oct 10, 2019, 05:00 PM
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Nacelle Construction


The pic is just a reminder to install your motor and servo extensions before gluing on the second nacelle side. I'm using servos with 5" wires, so the ones in the nacelles need a 12" extension to reach the front of the fuselage, which is where the receiver will be. Also a question for Jeff: What kind of servo arms did you use? Even my longer arms aren't long enough to allow the servo to sit on the inside of the 1/4" MPF hatch.
Oct 10, 2019, 05:03 PM
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Where'd the picture go? Hopefully, here.
Oct 10, 2019, 06:16 PM
Jer. 29:11
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Thread OP
@Jay B. Scott, your build is looking good! I used inexpensive 9 gram servos, and the servo arm is just shy of 3/4" long.

P.S. I have no experience with hot glue.


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