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Author Topic: Eureka!!!!  (Read 2264 times)
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Olbill
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« on: September 27, 2016, 02:06:59 PM »

To me the most aggravating part of building a low ceiling catapult glider with foam flaps is attaching the flaps to the forward part of the wing. I've mostly used 5 minute epoxy for this. On my recent WIF8 rebuild I used thick CA. For this to work you must use a VERY thin coating of thick CA on the wood and then push the foam against it. If you use too much CA the foam will melt. If you use too little you'll be left with gaps where the flaps aren't attached - which means getting out the epoxy to fill in the gaps. And - if you screw up - you will probably be cutting the flaps off for a second try.

Today I received a Bondic kit from Amazon. Bondic is a polymer that hardens with exposure to UV light. It ain't cheap. The kit was about $30. The kit contains a small tube of the liquid, a small UV flashlight and some application tools.

The catch to Bondic is that the liquid will only harden if it can be reached by the UV light. If you try to glue two opaque materials together with a glue joint between them, then the UV light won't reach the liquid and it won't harden. I thought since the foam is translucent there might be a chance that Bondic would work for a flap joint.

I set up a quick test by slicing off the edge of a .033" sheet of balsa to give a straight edge and then did the same with a scrap of .022" Durobatics foam. I put the balsa and foam on a sheet of waxed paper and then applied the Bondic liquid to the edge of the balsa. It came out in a series of small dots that I spread out with a scrap of balsa. I pushed the foam against the balsa and held the ends tightly together with my fingers while shining the UV light on the joint. I moved my fingers and the UV light down the length of the joint while pressing the pieces tightly together. The result was a perfect (at least by my standards) joint.

There was a small area about a half inch long that didn't get glued. That made the second miracle possible. I squirted a little bit of the liquid into the gap, hit it for a couple of seconds with the UV light and the spot was fixed.

If you're building flapped gliders you have to give this a try. It's amazing!
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Eureka!!!!
Eureka!!!!
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Maxout
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« Reply #1 on: September 28, 2016, 10:01:01 AM »

Bill,

 Have you tried foam safe ca? Another adhesive to consider is Uhu. A lot of the foamie R/C guys use it.
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ram
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« Reply #2 on: September 28, 2016, 10:36:29 AM »

Bill,

Can you bring this to Rantoul?  I'd love to see it.

Rey
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Tapio Linkosalo
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« Reply #3 on: September 28, 2016, 11:41:29 AM »

Also, have you tried slow-curing laminating epoxy? Quite thin stuff, so you could smear a small amount on the balsa edge, push in the foam, pin down to cure. It takes some 60 minutes to start curing, so there is plenty of work time, and then 14 hours to cure. But heating up to 60C shortens the curing time to just a couple of hours.
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Pops
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« Reply #4 on: September 28, 2016, 12:01:00 PM »

Today I received a Bondic kit from Amazon. Bondic is a polymer that hardens with exposure to UV light...

Reminds me of a product I saw advertized and tested around 20 years ago but never got around to check out myself: Solarez. http://solarez.com/
Maybe it's the same thing?
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Pops
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Olbill
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« Reply #5 on: September 28, 2016, 03:39:15 PM »

Thanks for all the suggestions! There are some UUUGE advantages to Bondic:

Vs. CA (any kind) - no need to get the parts perfectly aligned when they make first contact.

Vs. epoxy (any kind) - no waiting for curing and no need to hold the parts in perfect alignment during curing.

Tonight I'm going to re-flap my previous WIF8 wing to have as a backup.

Rey - I'll have the Bondic with me at Rantoul in case repairs are needed and will try to bring some scrap material along to demo it. I'm thinking that other uses for this material are going to come along in time.
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dslusarc
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« Reply #6 on: September 28, 2016, 04:20:32 PM »

They also sell a UV glue at Walmart or Target for $9.99 usually under the name like Lazer bond or 5 second fix. I have used it on some RC related parts. Not sure if the same quality as Bondic. How was the weight gain?
Don
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Olbill
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« Reply #7 on: September 28, 2016, 06:23:35 PM »

Don
I just finished re-flapping my WIF8 wing but forgot to weigh the parts before joining. The glue is a gel that seems to be about the same consistency as thick CA so I guess it's about the same weight. Another advantage over CA is that you can spread the gel out over the work piece and wipe off any drips or runs before you do the joining.

My first wing half worked great. On the second half I didn't have the pieces flush for about an inch of the wing tip so got a bump at the joint. I was able to run a double edge razor blade between the pieces to separate them and then reglue the tip.
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hklam
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« Reply #8 on: September 13, 2018, 12:28:47 AM »

The other possible solution which I found quite workable is using small dabs of canopy glue applied using a toothpick. And it is positionable before fully dried or cured, and once dried it is clear colored.

hklam
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flydean1
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« Reply #9 on: September 13, 2018, 08:49:01 PM »

I tried Bondic to adhere CF to ribs on a gas model.  Anything is easier than the classic medium CA rubbed down.  Never could get a consistent bond with CA and my caps had bumps.  Tried Bondic, and it was MUCH easier to manage, but I felt the bond was not complete on the theory that the UV light was only getting to the edge of the glue line.  Admittedly it was only about 1/16 to 3/32 wide.  So, it worked OK but kinda pricey.

Working with alternatives.  Will try RC-56 next.

Has anyone tried the "tacky" glues?  It smells like RC-56.
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atesus
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« Reply #10 on: September 13, 2018, 11:22:11 PM »

I've used Aleene's Tacky Glue for canopies with good results. It works similar to RC-56 canopy glue in my experience. I got a "Trial Tacky Pack" and the one I ended up using the most was the Fast Grab kind, then the original kind, IIRC.
--Ates
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dohrmc
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« Reply #11 on: December 27, 2018, 02:26:14 AM »

If you want to make sure the UV resin is fully cured, put it out in the sunlight got a while. Works very well when I tie fles using the stuff.
You might have to get creative protecting from wind, but sunlight works better than the uv lamps. I do the initial work inside, then take it out once things are pretty well set, for a final cure.
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Tmat
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« Reply #12 on: December 27, 2018, 10:46:45 AM »

I tried Bondic to adhere CF to ribs on a gas model.  Anything is easier than the classic medium CA rubbed down. 
Flydean, I've always used epoxy to apply carbon caps. Slow cure.
I create a very basic jig that is used to build the wing or stab and add a small finishing nail in the base of the jig at each rib location (the nail is horizontal). I wrap 1/8" rubber strip around each nail and up over each cap and rib. The caps are held in place with little tags of Scocth Magic mending tape.

Tmat
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F1B guy...
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flydean1
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« Reply #13 on: December 28, 2018, 12:12:01 AM »

Interesting Tmat.  I scored some spring-loaded hair clips from a Sally Beauty Supply.  They're sorta like metal clothes pins.  Then took some magic mending tape loops that was stuck to the ends of the clips which were fastened to the ribs with the tape, slick side inside, holding the cap strips to the ribs.  Worked fairly well.  Worked the Bondic "cure" light along the firmly positioned strips.
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cglynn
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« Reply #14 on: January 02, 2019, 08:31:08 AM »

I've used Aleene's Tacky Glue for canopies with good results. It works similar to RC-56 canopy glue in my experience. I got a "Trial Tacky Pack" and the one I ended up using the most was the Fast Grab kind, then the original kind, IIRC.
--Ates

Based on this, I picked up some Tacky Glue from the local craft store.  It worked great for adhering XPS foam flaps to the balsa TE of my latest F1N.  Weight gain was minimal, strength is excellent (my 6 year old son even proved that it is pretty good at withstanding shear loads), and the dry time is reasonably short.  I have developed a sort of work flow where I will glue the foam to balsa right before bed, and have yet to have Tacky Glue not completely cured by morning.  Needless to say, I like this stuff. 
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