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Old Dec 28, 2011, 07:18 PM
Time for me to Fly...
Mr. Wiz's Avatar
United States, MI, Fenton
Joined Jan 2000
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Question
Epoxy and micro balloons

So I've started on my Katana on a Blaster fuse build today. I'm using Paul Naton's Handlaunch building clinic video as a guide. When I mixed up my 30 minute epoxy with micro balloons for joining the wing halves it kicked off really fast like 15 minutes at most. Do the micro balloons accelerate the process? I measured out my equal parts with some plastic spoons so I know that wasn't an issue. Do the micro balloons make the mixture weaker? Should I be concerned at all by this?
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Old Dec 28, 2011, 07:40 PM
Throw it like you hate it
RCPC's Avatar
United States, CA, Castro Valley
Joined Apr 2007
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This happens to me too. Microballoons make the epoxy kick faster. Adding them makes the joint slightly weaker but you will be using a wrap over the seam of the wings. The wrap takes all the load. I have even heard of come people foregoing the initial joining of the wing halves and proceed directly to the wrap. I wouldn't be worried. By the way, how much in proportion of the mix was accounted for by microballons?
Paul
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Old Dec 28, 2011, 07:50 PM
Hey was that a Thermal ????
Joined Nov 2009
2,448 Posts
This happens all the time. You will be fine as Paul said the wrap is the key. The main purpose of the filler is to give you some nice HP's to put your bolts through.

Paul
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Old Dec 28, 2011, 07:52 PM
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dc812's Avatar
Chula Vista, CA
Joined Jul 2006
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+1 additives cause 5/15/30 minute epoxies to kick extra quick. I don't even try to additives in 5 minute any more....... too much stress.
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Old Dec 28, 2011, 08:01 PM
Hey was that a Thermal ????
Joined Nov 2009
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Quote:
Originally Posted by dc812 View Post
+1 additives cause 5/15/30 minute epoxies to kick extra quick. I don't even try to additives in 5 minute any more....... too much stress.

MB and 5min can be used to start a fire !!!!LOL
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Old Dec 28, 2011, 08:06 PM
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wyowindworks's Avatar
Cody, WY
Joined Nov 2007
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The reason the MB causes the resin to kick faster is that it causes the resin to hold more heat rather than dissipate it. MB are hollow so the function like an insulator. Typically anything that is hollow will cause this. Some fillers help the resin dissipate heat and cause it cure slower.
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Old Dec 28, 2011, 09:49 PM
Time for me to Fly...
Mr. Wiz's Avatar
United States, MI, Fenton
Joined Jan 2000
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OK so MB causes the epoxy to kick sooner an I shouldn't be alarmed by it. That's good. I guess it would be better to get some slower epoxy for the next one.

Question: I have some 1.5 oz glass cloth. Is that heavy enough for the center strip? I plan on using some Pacer Zpoxy laminating resin for this process.

Also, since this is a Blaster 3 Fuse I'm contemplating putting all the servos in the pod like the Blaster. Is there any reason I shouldn't do that with this wing?
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Old Dec 28, 2011, 10:01 PM
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Mr. Wiz:

For the filler in the joint, yeah, slower epoxy. I use 1-hour.

For the wrap, I highly recommend West Systems epoxy. The small portions will last you some years, and you will love it. You must also have an accurate scale to measure out the portions (by weight!). I am using the 105 epoxy and 205 hardener at the moment. Aircraft Spruce, among many other suppliers, carry West Systems. Figure on 20 minutes working time, so have everything ready to go.

Your glass should be OK. If you're anxious about the wrap, here is something I have done: a thin strip over the joint, then a second, wider strip. I put both on in the same episode. It will be strong enough.

There should be no reason not to put all four servos in the fuselage. It's ironic, though. I used the money you gave me for the Taboo towards two Blaster 3s, and I put the aileron servos in the wing! I like RDS or top drive too much to stand for all that hardware out in the breeze. It's a personal problem I have, you need not be influenced by me.

Good luck!

Yours, Greg
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Old Dec 28, 2011, 10:11 PM
Registered User
United States, CA, Tehachapi
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I used 6 layers of .5oz glass to join my last wings, each layer a little smaller than the last to avoid stress risers. It feels solid as a tank. I don't throw to the moon, though...yet...
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Old Dec 28, 2011, 10:35 PM
No conspiracy in theory
skorski's Avatar
Oak Ridge, Tenn.
Joined Aug 2004
3,635 Posts
bwill6,
I would have thought to start with the narrow & progress wider.
Seems to me i've gotten smoother finishes that way.
(just thinkin)
Mike.
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Old Dec 28, 2011, 11:10 PM
a.k.a. Bob Parks
Glendale, AZ
Joined Jun 2008
2,308 Posts
Easy to find West Systems dealers:

http://www.westsystem.com/ss/where-to-buy/

& put in Fenton, Michigan or your Zip Code.

Looks like there are lots of places that carry it. I use the 206 & 207 hardener, 207 especially in the hot Phoenix summers. A quart can lasts a long time for standard builds & repairs, maybe not do long if you are making your own wings.

BP
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Old Dec 28, 2011, 11:21 PM
G_T
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Joined Apr 2009
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I have used two layers of glass to join. Each layer is 1/2" wide, and they are offset about a third of their width to each side of the centerline of the wing. The overlap gives two layers in the middle. The non-overlap gives one. 1.2oz glass should be fully sifficient this way. I used biased for the orientation, but either way is ok.

Usually I was lazy though and used a half inch wide center strip, and a roughly one inch wide strip over the top of that. I've used glass, Kevlar, and carbon. Use whatever you want. It will all work.

But don't skimp on the hardpoint. I like having cotton flox and milled fiberglass as fillers, instead of microballoons. The result is the same density (cotton is a light weight filler) but much stronger and it is not brittle. Epoxy with microballoons is brittle and weak.

Actually, I don't like microballoons for anything. West 410 is better than the usual microballoons by quite a margin IMHO. I've used it for some things.

When joining wings, one can use a shortcut method if you are in a hurry. Have the hardpoint areas dug out, and an area by the spar rods and a little area right at the leading edge. Mix up some 5 minute epoxy and add in filler of choice. Mix fast but make sure the epoxy is mixed before adding the filler(s). Quickly scoop and scrape this filler into the recesses you put in a wing root. Level it, and then let cure sufficiently (doesn't take long). Mix up some more, and join. Probably use 15 min for the joining to give more working time. It may help to tape the bottom together first with clear packing tape, to help with alignment, then fold open for the epoxy work. Have a half wing bed ready, and books or whatever as a support for the other wing tip. Epoxy, drop on bed, and put a little weight (gently - perhaps use a top bed) on top to anchor in place. Wipe up any oozing epoxy. If there isn't any oozing epoxy, not enough was used! You only really need the epoxy at the hardpoints and perhaps a smidgen at the trailing edge. The rest gets glued anyway when the reinforcing fabric is added.

Gluing the foam together accomplishes essentially nothing except adding weight. Putting pinholes in and stuffing with glue is even worse.

Oh, thicker CA will work for the glassing work, but it is not nearly as good as using laminating resin. Wrap a finger with electric tape, and use that to smear out and rub in the CA. Blot up excess. Let cure. DO NOT USE KICKER!

You DID use 3M77 mist to anchor the center fabric in place, before wetting out with your glassing agent of choice???

Gerald

PS - Sorry, I got typing again.
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Old Dec 29, 2011, 07:40 AM
Time for me to Fly...
Mr. Wiz's Avatar
United States, MI, Fenton
Joined Jan 2000
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Quote:
Originally Posted by glidermang View Post
Mr. Wiz:

For the filler in the joint, yeah, slower epoxy. I use 1-hour.

For the wrap, I highly recommend West Systems epoxy. The small portions will last you some years, and you will love it. You must also have an accurate scale to measure out the portions (by weight!). I am using the 105 epoxy and 205 hardener at the moment. Aircraft Spruce, among many other suppliers, carry West Systems. Figure on 20 minutes working time, so have everything ready to go.

Your glass should be OK. If you're anxious about the wrap, here is something I have done: a thin strip over the joint, then a second, wider strip. I put both on in the same episode. It will be strong enough.

There should be no reason not to put all four servos in the fuselage. It's ironic, though. I used the money you gave me for the Taboo towards two Blaster 3s, and I put the aileron servos in the wing! I like RDS or top drive too much to stand for all that hardware out in the breeze. It's a personal problem I have, you need not be influenced by me.

Good luck!

Yours, Greg
Greg,

I'm not completely sold on putting the servos in the Pod. I just think having a plane that doesn't require me to connect wires is an advantage. I had one of the servo wires break off the connector on the Taboo at my firsr contest which put me out of business for the last three rounds. Fortunately, it got too windy and they didn't fly the last two.

Let me ask you a question... On you planes does the wing sit down tight to the boom? With my wing it will be held up off the boom about 3/8". I don't like the idea of having a servo connector hanging out in the breeze.
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Old Dec 29, 2011, 08:07 AM
Aurora Builder
United States, MD, Lusby
Joined Nov 2003
3,437 Posts
Center strips should be done on a 0-90. Bending loads are the highest in the center and you are doing virtually nothing for torsion in this area. The extra fabric density of sheared bias cut cloth does not make up for the reduced strength due to off-axis fiber orientation. To top it off, 0-90 strips are easier to lay down properly with 3M77.

These days I am using 0-90 2oz carbon to join my wing halves, with the procedure Gerald outlined (although I do everything in one shot with 15 minute epoxy and West 406 filler). In the past I have used a single wrap of 1.6oz glass, with small (1"x1") doublers over the spar caps. Plenty strong. 2 layers of 1.2oz glass will likely be stronger than 1x 1.6oz, and weight will be similar between the two.

Servo wires can fail, yes, but electrical connections are, imo, much more reliable than taking on and off mechanical connections (if you want to keep those connections lightweight). If you really want to be slick, take a look at how Oleg wired his Validol, it is a plug and play system, chances of a wire breaking loose are very, very slim. That's my opinion, ignoring the fact that in-wing servos are better for flutter.
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Old Dec 29, 2011, 09:19 AM
Time for me to Fly...
Mr. Wiz's Avatar
United States, MI, Fenton
Joined Jan 2000
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Alright... So, I'm going with 2 layers of 1.5 oz glass on the center. Should be good. Then I'm sticking the servos in the wing and I'll see if I can make a plug like Oleg did.

Thanks!
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