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Old Feb 03, 2014, 09:22 PM
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Deer Park, Tx (East side of Houston)
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Robart pin hinge in an ARF - first time user

Ok, so I studied on Robart pin hinge, bought enough 3/16" dia. (middle size) for the whole plane, even bought the drill guide...I get it...but then again I don't.

Each half of the hinge needs a hole drilled about 1 and 3/8 inch deep, it is a long pin on them.

If the flight surfaces were not covered I would glue blocks in where I was going to put a hinge so the whole pin was glued in a solid wood block inside the surface.

But my surfaces are covered, 25% Sbach ARF. I have started with rudder. Shining a light through the covering it appears the wood the pin will glue in is only 3/4 inch deep.

I am not doubting everything I read, and I acknowledge I have zero experience.

Tell me I am over thinking this. Tell me to clean the hinge well to remove mold release agent, rough up the pin with some sandpaper, put a little grease to keep epoxy from where it is not supposed to be, and glue them in with 30 minute epoxy to what wood I have and not to worry about the details so freaking much :-)

At this rate it will be next year before I fly it. If I could just get one surfaced hinged I'm sure the pace will pick up. Learning curves are slow.
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Old Feb 03, 2014, 10:52 PM
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United States, NY, Eldred
Joined Jun 2012
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If the pin will be in 3/4", that will be fine. Just make sure you don't drill the hole too big so the pin has some resistance. Not that epoxy wont do the job, but since you cant see what's going on beneath the covering, you may want to consider using Gorilla Glue. It swells in the hole and hardens.
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Old Feb 04, 2014, 09:48 PM
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United States, MI, Macomb
Joined Apr 2009
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I read a thread on the use of glues other than epoxy for installing Robarts. One of the glues was "canopy glue" which I thought was strange, so I did a test with it and was totally suprised. I could not pull the hinge out of the balsa.

Some guys just hate working with epoxy, especially around Robart hing pins.

DanWard, Just because you see 3/4 inch of balsa thru the covering at the trailing edge does not mean you actually have 3/4 inch of SOLID wood. Some trailing edges are made with a small solid rail with balsa sheeting on top and bottom that extendes beyond the solid stock.

I would drill a small test hole to check how much solid stock you actually have.
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Old Feb 04, 2014, 10:08 PM
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Deer Park, Tx (East side of Houston)
Joined Oct 2009
142 Posts
Thanks for the input.

I am familiar with Gorilla glue but not canopy glue so I guess I have more Googling to do.

I plan to put the Robart hinge at the plane manufacture suggested location in place of provided CA hinges. As near as I can tell it is full 3/4" thick balsa, at least on the rudder which is where I am starting.
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Old Feb 06, 2014, 06:30 PM
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United States, IA, Rockwell
Joined Jul 2011
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FWIW take a look at these two threads to help ease the installation of the hinge points. Take what you want and throw the rest away

http://www.rcgroups.com/forums/showthread.php?t=1837222

http://www.rcgroups.com/forums/showt...t=robart+drill

Ken
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Old Feb 07, 2014, 01:35 PM
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Deer Park, Tx (East side of Houston)
Joined Oct 2009
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Group,

Two bullet points for ya in my ongoing effort to not screw up my first install of Robart hinges.

1. What is the proper insertion depth for a Robart pin? Should the center of the pivot pin in the hinge be centered where the two surfaces join? Or should the pivot pin be slightly counter sunk into one of the two surface? For example slightly countersunk into the aileron? Or centered where the aileron meets the wing?

2. kenh - Thanks so much for the tip on blind transfer punch and link to the two threads. The threads were highly reassuring!

I did not know what a blind transfer punch was much less how to use them or where to buy them. Living in a city the size of Houston I felt sure someone would have them but nothing was in stock anywhere in the Robart 3/16" size. I could go buy them today 1/4" and larger but that was no help

So I called McMaster-Carr and next Tuesday I will be the proud owner of a set of six.

Even though I am hinging an ARF that is pre-covered and thus pre-beveled this addition to my tool set will remove a bunch of risk associated with not getting the hole in the same place on both parts. Really cool!

Robart hinge points still seem much more complex to install than any other hinge I have ever used but from everything I have read they are greatly preferred by many especially in the larger scale stuff.
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Old Feb 07, 2014, 08:08 PM
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United States, IA, Rockwell
Joined Jul 2011
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Quote:
Originally Posted by DanWard View Post
Group,

Two bullet points for ya in my ongoing effort to not screw up my first install of Robart hinges.

1. What is the proper insertion depth for a Robart pin? Should the center of the pivot pin in the hinge be centered where the two surfaces join? Or should the pivot pin be slightly counter sunk into one of the two surface? For example slightly countersunk into the aileron? Or centered where the aileron meets the wing?

For your ARF I would split the difference. Put the hinge centered between the two surfaces.

2. kenh - Thanks so much for the tip on blind transfer punch and link to the two threads. The threads were highly reassuring!

Your welcome!

I did not know what a blind transfer punch was much less how to use them or where to buy them. Living in a city the size of Houston I felt sure someone would have them but nothing was in stock anywhere in the Robart 3/16" size. I could go buy them today 1/4" and larger but that was no help

So I called McMaster-Carr and next Tuesday I will be the proud owner of a set of six.

Even though I am hinging an ARF that is pre-covered and thus pre-beveled this addition to my tool set will remove a bunch of risk associated with not getting the hole in the same place on both parts. Really cool!

Robart hinge points still seem much more complex to install than any other hinge I have ever used but from everything I have read they are greatly preferred by many especially in the larger scale stuff.

After the first install you will be an expert. They are really no more difficult that the other style of hinges. If you break one it is easy to drill them out and replace them See this thread. http://www.rcuniverse.com/forum/cras...p-232-a-2.html Hinge replacement starts at post #35

One trick I've learned is to hinge ONE surface at a time until you've get use to the hinge points. When hinging a surface you will use a slow setting glue so as to be able to glue BOTH side of the hinges at one time. You will apply glue to all the holes in both, lets say the rudder and the vertical fin, at the same time. Insert the hinges in the rudder and immediately put the other half of the hinge into the fin. Now flex the rudder back and forth a couple of times. This will automatically assure all the hinges have the hinge pin perfectly in line with the other hinge pins.

If I were you I would "waist" a piece of balsa and do a test hinging except do not glue the hinges. You can experiment with how the pins are aligned to see what I'm talking about.

Take a look at this tutorial. I think it may help you out some. In fact this whole site is a wealth of knowledge. I visit it often even when "I know" how to do something to get another spin on the procedure.

http://www.airfieldmodels.com/inform...ints/index.htm

Ken
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Old Feb 12, 2014, 02:12 PM
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Deer Park, Tx (East side of Houston)
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OK, I got my blind transfer punches yesterday. I have read all I can, watched the videos and think I am one answer away from taking the plunge and hinging my first surface.

Speaking of taking the plunge, those that know me know that for me to drill holes that are plumb, square, perpendicular, or even parallel with other holes is a challenge for me.

I have the robart drill guide, I have the blind punches, both of which should help reduce risk.

I tell myself if the holes line up at the pivot point but are a bit cockeyed in the direction of travel it won't matter much since that is the direction the hinge is designed to move in.

But if the holes line up at the pivot point but are cockeyed in any direction other then in the range of normal hinge motion...it can't be good.

So I recon I will:

1. l will scribe a line across the hinge line that is perpendicular to the hinge line and then separate the two surfaces

2. drill the first set of holes using the robart drill guide and attempt to run the drill parallel to the line I scribed.

3. Then transfer the holes to the mating surface with my blind punches.

4. And then even though the points I transfer may not be exactly where the scribed line is, I will again use the robart drill guide and attempt to run the drill parallel to the line I scribed, right?

I bet once I get a few surfaces hinged I am going to look back at my post in this thread and laugh ways saying to myself, "You silly old man!"

Have a blessed day and thanks for all the help.
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Old Feb 12, 2014, 09:33 PM
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United States, IA, Rockwell
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Don't worry about the line on the surface you have not drilled. ALWAYS drill where the transfer punch has marked. Highlight the point with a black pen and sight through the drill guide when drilling the hole.


Take the time to glue a little sand paper on the wings of he drill guide. The guide will stay in place much better.

Ken
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Old Feb 19, 2014, 10:19 PM
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Deer Park, Tx (East side of Houston)
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Ok, it is official. I think Robart pin hinges are the devil and one giant pain in the to install. I sure wish I had a friend to show me how it is done because I just don't get it.

Despite spending a lot of time at the hospital with my 96 year old dad I have been working on hinging just my rudder. Tonight all holes drilled and all dry fit. I am just not impressed or am doing something wrong. I just don't get the hype.

I am not the most experienced modeler but I have assembled 6 prior ARF up through 57". And they all used CA or Dubro style hinges. They all look and fly great with excellent hing lines and minimal hing gaps.

But for some reason I have it in my head that 1/4 scale should use 3/16 Robart hing pins and I have no experience with them.

Being ARF there just isn't that much material to glue to, a wider hing would have more glue surface area. I was planning to use 30 minute epoxy but I can now see where expanding foam gorilla glue might have benefits inside the surface.

The tapered shank of the pin sure makes drilling the hole fun. The best thing I own is a tapered reamer. Drilled 3/16 and then tapper reamed until pin would sink in till center of pivot is just visible.

I push the two surfaces together and have a nice hing line. Then I move the surface to line pivot orientation and check 3D travel but as I do the pins pull themselves out.

I just don't get it. I could have hinged the whole plane with Dubro and pinned every one in the time I have spent on just the rudder. And I am still not happy enough to glue them.

Got to be back at hospital early AM. Going to bed frustrated...
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Old Mar 10, 2014, 01:35 AM
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Florida
Joined Dec 2001
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I just use a file or an X-Acto to trim around the hole opening until the thicker part of the hinge goes into the wood. If the wood is soft enough a lot of times you can just push the hinge in and out a few times and no cutting or filing is necessary.

You just need someone to show you how to do this in person. Hinge points are in my opinion the easiest of all hinges to install. Well, easiest of hinges I would use anyway.
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Old Mar 12, 2014, 03:35 PM
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United States, NY, Oneida
Joined Feb 2013
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robart hinges

What part of installing the hinges is giving you a problem? Maybe your thinking this thru to much. what size plane is it your hinging? I would not gorilla glue because it is a expanding glue you have to babysit it making sure it doesn't push the hinge out of the surface you are hinging also you need to keep wiping the excess glue away from the hinge for 10 to 15 minutes will the glue sets up. I would stick with epoxy. As long as your hinge lines are centered and your drill jig is centered you should be fine. Take your time and relax it really is easier then it looks in this hobby its all about relaxing and enjoying the hobby.
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Old Mar 12, 2014, 04:42 PM
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United States, TX, The Colony
Joined Nov 2012
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I installed some in an elevator whose CA hinges had cracked. I wish I had the jig, but I didn't have any issues. A 1/8" drill bit and 1/2" countersink bit to create clearance for the hinge point, and no issues. I used canopy glue on the advice of my lbs. Much easier to clean up than epoxy.
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Old Mar 15, 2014, 02:44 AM
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Canada, MB, Winnipeg
Joined Apr 2008
872 Posts
Pacer hinge glue. Epoxy does not stick to the pin hinge material. Melt Vaseline and use a Q-tip to dap a little on the joint. I use a conical burr tool to open the hole for the knuckle of the pin. Use water on a Q-tip to wet the wood hole before applying glue. A little Vaseline on the surface edge around the hole keeps the two surfaces from sticking together. When you glue them in just bend the surface enough to get the deflection you want and no more. If your worried about the depth then add an extra pin or two to each surface. Robart pin hinges move so effortlessly you can add more without adding any strain to your servo.

http://www.horizonhobby.com/products/PAAPT55 Comes with a nice applicator.
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Old Mar 16, 2014, 09:42 AM
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Quote:
Originally Posted by DanWard View Post

I push the two surfaces together and have a nice hing line. Then I move the surface to line pivot orientation and check 3D travel but as I do the pins pull themselves out.
I get what your saying here. Seems to me the only way for it to "bind" and pull the pin out is for the surfaces to come together. This seems like it (the control surface) is not beveled properly for the throw it needs to achieve.

I know its really basic (like askin if you have gas in it ) but since there are no piccys we have to ask. Is the mating surface beveled?
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