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Robart Hing Point Experiment

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Robart Hing Point Experiment

Old 02-28-2010, 04:54 PM
  #1  
Flyin Beagle
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Default Robart Hing Point Experiment

I posted this in the sticky above as well, But I thought it may be noticed a little more here.

After reading all of the debate in the posts in the sticky above about the proper adhesive for hinge point installation, I decided to do a little experiment. I was preparing for my first installation of the hinge points and decided to practice on some scrap balsa prior to screwing up my new ARF. I used a piece of 1/2" square balsa stock and followed the techniques described above including dampening the holes for the gorilla glue prior to installation and using a toothpick to make sure the glue is completely coating the inside of the holes. Picture one shows the setup I made. The two types of glue used were titebond III, and gorilla glue. After putting the setup together I left it alone for approximately 18 hours. After the setup time you can see in picture 2 and 3 what the dried glue looks like on the outside of the holes. Obviously I did not baby sit the installation or clean away the excess glue because I wanted to see how much foam would really occur. The theory on the gorilla glue foaming up and creating a big blob on the backside of the hole obviously doesn’t happen, and I would consider this glue to be negligible in the holding strength of the hinge. Picture 4 shows the straps (dog leashes) that I used to pull on the hinges. I stood on one end and pulled on the other with my arms until something failed. As you can see in the 5th picture the titebond hinge pulled out of the wood, and the Gorilla glue hinge failed at the actual hinge itself. Upon closer examination of the titebond hinge it appeared that I did not have much glue if any in the hole so I tried again. The results of the retrial can be seen in the last picture as the titebond held very well and the actual hinge itself failed.

Soooooo.... after all of this I learned it doesn’t matter what glue is used; it is all in how careful you are in the installation. I was surprised at how strong these things were. Even in the first titebond failure I had to pull very hard to get it to fail (hard enough that I bopped myself in the eye when it let go). After this experiment I completed the hinging of my ARF, and the process went very smooth and resulted in a good strong free moving hinge with almost no gap at all. I really liked working with these hinges and will use them again in the future.
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Old 02-28-2010, 07:33 PM
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p100d
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Default RE: Robart Hing Point Experiment

These are the only hinges I use. I love the "freeness" of the control surface. They also give great throw. If installed at an angle they work great for flaps, giving realistic deflection. When building a model I use 1/4" triangle balsa on both control surfaces with a gap to install the hinge. Works great to give no gap at all between the surfaces. I have always used epoxy to install. Put a little oil on the pin with a pin and the epoxy doesn't stick to it. The glue looks good though.
Old 02-28-2010, 08:22 PM
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Default RE: Robart Hing Point Experiment

I just started useing gorilla glue last summer after seeing a 3-D 35% crash and all the hinges held tight....not mine! LOL
I have always used epoxy.
IF I use any water useing gorilla glue is on the hinge point only and I shake off any excess. Sometimes I don't use any water.
Too much water in the hole only makes the foaming worst.
If you read the instructions it talks about useing water for hardwoods......balsa is NOT. )
Make sure you squeeze out the air from the bottle or you will be buying more glue.
Jim
Old 02-28-2010, 09:51 PM
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Default RE: Robart Hing Point Experiment

Very good experiment. I was going to do the same experiment myself. now I don't have to.

I always like lesson learning threads.
Old 02-28-2010, 11:03 PM
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Default RE: Robart Hing Point Experiment

I did basically the same experiment with canopy glue. I couldn't pull the hinge out at all. So I have been using canopy glue to install all my hinges in my 50CC size planes. The canopy glue is very easy to clean up. If some glue gets in the hinge point, just move the joint a few times and it loosens right up.
Old 03-01-2010, 06:45 AM
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Default RE: Robart Hing Point Experiment

thanks for posting this.
Old 03-01-2010, 08:01 AM
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Flyin Beagle
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Default RE: Robart Hing Point Experiment

One other thing I should note that I found in my experiment. In the sticky at the top of the page some people warned of using epoxy because it does not bond to the plastic of the hinge itself so the strength of your joint is totally mechanical. I found that the gorilla glue bonded very well to the hinge point plastic and was pretty difficult to scrape off using a metal pick, but the titebond would flake off relatively easily by just using my finger nail. I dont think this really makes a difference because as you can see above either glue joint was stronger than the hinge itself.
Old 03-03-2010, 09:34 AM
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Default RE: Robart Hing Point Experiment

Nice experiment. You could have a future as a Mythbuster.

I always use Pacer hinge glue, but it's good to know that other glues work just as well.
Old 03-14-2010, 03:32 AM
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Default RE: Robart Hing Point Experiment

I too use canopy glue RC56. It actually sticks to plastic and is as easy to apply as Titebond. I once did your experiment using a 3/4" balsa block, and the hinge failed before the glue did.
Old 04-02-2010, 01:46 AM
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Default RE: Robart Hing Point Experiment

Umm, Ochroma Pyramidale or Balsa is the softest of the commercial hard woods, so the water advice is probrably true.

hugh

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