Which glue is best for robart hinges?
 

I need to put robart hinges on my new Great Planes Super Stearman because the hinge slots were cut off center. I have never used these before. I read the article and the posts on this. Would canopy glue be a good choice for this? HELP!!

RE: Which glue is best for robart hinges?
 

I use epoxy, usually 12 min variety. Be sure to put the epoxy into the hinge hole, never on the hinge (because on the hinge point, it is more likely to work itself into the hinge itself, where you don't want it to be.

Do a carefull prep of the hole(s), be sure to expand the opening near the edge so that the bigger part of the hinge point will fully seat, giving you minimal hinge gap. I use a phillips screwdriver as a countersink tool to expand this opening.

Glue one surface at a time, i.e., hinge the elevator, let the epoxy cure, then attach the elev to the stab, etc.

Take your time, do it right, and you will have the best hinge available.

Good luck.

RE: Which glue is best for robart hinges?
 

For hinges-gorilla glue as it expands to fill the hole. DO NOT use gorilla on any surface that vibrates (i.e. firewall) as it ain't the strongest glue on earth in those applications. Also, for your hinges make a aluminum foil cup and melt some vaseline in it with your heat gun. Bend the hinges and dip the hinge portion in it and allow to cool. This protects the hinge area from glue (whatever you choose to use).

RE: Which glue is best for robart hinges?
 

Is it O.K if the wood you are putting the hinge into allows the hinge to penetrate clean through and not be entirely covered with wood?

RE: Which glue is best for robart hinges?
 

It's best if you have full hinge coverage but if you have more than half in the wood you'll be ok using the Gorilla glue. Just don't go crazy with the Gorilla glue. It expands something fierce and all the excess will run down the covering inside the wing.

RE: Which glue is best for robart hinges?
 

Elmer's Ultimate polyurethane glue (same as Gorrilla, 1/2 the price). Here's how I do it:

1) drip 4 or 5 drops of water into the hole (I like to do the control surfaces first).
2) drip one large drop of poly into the hole
3) using a can of air or toothpicks, drive that drop of glue down into the hole.
4) walk away for a few minutes and allow the glue to run into the hole
5) come back with a Qtip and wipe away the glue (spinning motion) from the socket
6) insert the preoiled hinge point to the halfway mark, check for 90 degrees perpinduclar to surface by flexing hinge down and 'eyeing' it.
7) after 3 or 4 hours, the hinge is set.

I use light machine oil on my hinge knuckle, just a drop, flex the hinge, and wipe away excess. If it's an ARF with not enough 'meat' , i knurl the hinge point closer to the knuckle with a pair of dykes or the like.

I also recess my hinge point holes with the cone shaped grinding stone on my dremel.

RE: Which glue is best for robart hinges?
 

I disagree. I have used poly glue exclusively on firewalls and LG mounts for years. Maybe you got a bad batch of glue? I find epoxy is more likely to crack and break over time than poly glue.

RE: Which glue is best for robart hinges?
 

After having a G62 come loose in the air and got it back down I scraped and re-glued it (it did have full contact on 3/4" plywood) only to have it spit out again like a giant watermelon seed at 100' the second time. Oddly enough only a broken prop and a couple of bent fins and a few holes in the wings it was flying the next wknd. I called gorilla and they said that they didn't like high vibration areas

RE: Which glue is best for robart hinges?
 

I'm hinging a wing with Gorilla glue in the next couple of hours. I suppose I could post a pic or two to show how it expands out of a hole.

RE: Which glue is best for robart hinges?
 

Epoxy has been working for years. "If it ain't boke don't fix it" I use 30 miute epoxy. The longer an exothermic glue has to cure the better.

RE: Which glue is best for robart hinges?
 

Just to stir things along, I have used Sig Bond for this application almost exclusively for the past eight years. The wreckage pictured here was an 80" span 90FSR powered sport aerobatic machine shot down after approx 5 years of energetic working out.

As an exercise I dug out most of the hinges from here, cleaned them up and reused them in its similar design replacement. That one still gets regular workouts. Last flown about two weeks ago, it is showing no signs of any failure.

During installation I feed a small drop of sewing machine oil into the hinge itself and install both halves at the one time. I then clean any excess off the area with a cotton bud dipped in plain water. This method has never let me down...

Alan W

RE: Which glue is best for robart hinges?
 

True. But with hardness comes brittleness. I finished a 1/3 scale Lanier Extra 330 for a friend two years ago. The building done before I got it (10+ years ago) was stellar. Tight, and very little epoxy sqeezed out. But as I started to cover it, I noticed that a slight bump would shatter the epoxy and ruin the joint. Epoxy might work for a plane with a 3 or 4 year life span, but it would've wrecked this particular plane. Epoxy gets brittle and harder with age, just like cement. Polyurethane glue on the other hand...when it's cured, it's done.

I haven't used it on a plane that has a 50cc gasser. But on my 60 - 120 sized stuff, it can't be beat.

RE: Which glue is best for robart hinges?
 

I've used epoxy and Gorilla glue (not combined, but on seperate builds!). Both worked fine. Do an experiment with the urathane (Gorilla) glue so you can see how much you need (not much), and to see how much it expands and how long it takes. Don't just glue it and walk away, or you will get excess that may be tough to remove later. I "babysit" the glued hinges until I am sure it is done oozing out. If the hinge point goes clear through the wood, that's not a big deal, as long as you have enough "meat" for the hinge to grab onto. I've tried to melt Vaseline to lube/protect the pivot point, but find a drop of oil is easier for me. I make too much of a mess with Vaseline. I do use vaseline on other pinned hinges like GP or Dubro, as it covers more of the exposed hinge line on that style hinge.

RE: Which glue is best for robart hinges?
 

I use 30 min epoxy to install robart or similar hinges. I don't like how the gorilla glue expands and as said above if you don't babysit it you will have a problem. Before installing my hinges I scuff the area to be glued with sandpaper to get a better grip with the epoxy. Then I will put some vasiline on the hinge itself to keep the epoxy from sticking to it. I just installed similar hinges in a 50cc gasser with epoxy and haven't had any problems yet.

Austin

RE: Which glue is best for robart hinges?
 

All of the glues and methods work just fine.

Using Gorilla or Ultimate Urethane Glue

I used epoxy for many years but found that the Gorilla, or Ultimate, glue is faster and easier to work with, along with providing a longer working time. Plus it pretty much always fills the hole around the hinge, which is something you're never sure of with epoxy, especially if the hinge hole is not closed off inside the wing. When the hinge opening penetrates to an open area inside a wing you have the quandry of which way to set the wing while the glue dries. Do you want the excess or wet glue to go into the wing or out of the wing over the hinge? How much will remain around the hinge point? Generally when using epoxy the "down" side (as the wing lies) of the hinge has epoxy and the "top" has little to none. In a "perfect" world where the hinge pockets are closed on the interior end you can only do one side of a hinged surface at a time using epoxy since the surface will be left propped up to prevent the epoxy from running out. Then you have clean up with epoxy as well, and you have to catch it at the right time or you'll be chipping the stuff off forever.

As noted earlier, you have to clean up when using Gorilla glue as well but there's a way to avoid the "babysitting". I used to periodically check the expansion and wipe it away but it's been found that simply masking off the working areas with low tack tape around the hinge permits the glue to expand onto something that will not be on the plane later. Simply wait about an hour or so after glueing and go back over the hinges with a cloth or paper towel dampened with acetone to remove most of the expanded Gorilla glue and remove the tape. You can do both surfaces to be joined at the same time this way and not have to wait for one side to cure before doing the other half. Add a drop of 3 in 1 oil or similar to the hinge joint and you're done. You use alcohol for clean up with epoxy, so both use a chemical for that process.

As for which way is best? Beats me since all work pretty well, but I think for ARF assembly where you did not control the depth of the hinge pocket the urethanes are a better choice. I know that since using the urethane glues (Ultimate and Gorilla) I have not had a loose hinge point on an ARF when complete but that's just me. Pick a method that suits you and run with it. Use of the urethane glues is not limited to hinge points. The stuff can be used in any area where you may want a thin fill and have access for removing the expanded material. It's worked well for joining wing halves where a wing box and spar was used on an 18 pound biplane that flew pretty hard. Never failed or weakened. I don't believe I'd use it on a firewall, but, again, that's just me.

Here's some pictures of the process. Squirt a little bit of glue into the hole before you put any on the hinge, then slide it in and use a small piece of dry paper towel to catch the top and bottom excess. Of course the hinge joint has Vaseline on it to prevent the glue from entering the joint. Final clean up will come about an hour or a little more after joining the parts. I'll post some more pics when that comes around. Notice there's no mixing cup anywhere? Straight out of the bottle.

RE: Which glue is best for robart hinges?
 

I've been using this stuff for hinge points:

http://www3.towerhobbies.com/cgi-bin...?&I=LXCX67&P=7

Can glue get any more specialized?

RE: Which glue is best for robart hinges?
 

Yes, it can. If you're performing composite assemblies and lay ups it becomes very specialized indeed. And real expensive!

RE: Which glue is best for robart hinges?
 

Pat,
Tnx for the tutorial. I noticed you didn't mention moistening anything with water before gluing? Is that an un-necessary step?

Jim

RE: Which glue is best for robart hinges?
 

Gorilla Glue, finished product

If you follow the directions on the bottle you'll note where it mentions moistening the surface to be glued. The humidity where I live is always above 10%, which is the low number on the instructions, so I've never bothered to moisten anything. In doing this hinge job it's been raining for weeks so there's plenty of moisture in the air and wood to set things off. If I was to use water to add moisture the expansion would be even greater and it wasn't needed here. Where you are and what you are glueing will determine what you need to do regarding additional moisture.

In the following pictures I started with two pictures of the side that was on "top", then rolled the wing over to the bottom where liquids naturally migrate to so you could see the expansion and residual mess. Use a paper towel wet with acetone to wipe down the top of the hinge, removing the excess glue. Use one paper towel for each side of the wing to avoid carrying adhesive from one side to the other. Next I used a sharp #11 Exacto blade to cut the tape at the hinge line. Best way to do that is to lift the tape, roll it back towards the hinge line, and lightly cut it from the adhesive side to avoid cutting the covering or balsa hinge line. Do this on one side of the wing then roll the wing over and pull the remaining tape.

The finished product after removing the tape is in the final pictures. There was no additional clean up after removing the tape.

There are many different methods of glueing hinges. It doesn't hurt to try a few of them to see which ones you like the best or what works the best for a given hinge product or wing type. Times and products change so it often pays to move forward with the times when the change can benefit you.

RE: Which glue is best for robart hinges?
 

I run a moist Q-Tip swab into the hole prior to gluing with Gorilla.

RE: Which glue is best for robart hinges?
 

Tnx. Sound like dry wx, use Q-Tip.............wet wx no q-Tip needed (Pat). Right now on the rainy North Oregon Coast, I guess it would be no Q-Tip.....................and no flying! [:o]


Jim

RE: Which glue is best for robart hinges?
 

And also because of global warming?????????? pub

RE: Which glue is best for robart hinges?
 

I use Alan's method, an aliphatic, which is also one of Robart's recommendations. What's wrong with following the directions on the package?

RE: Which glue is best for robart hinges?
 

Global warming:

A cyclical event that takes place after every ice age, thought to be caused by periodic shifts in the earth's orbit about the sun when an exaggerated elliptical orbit shifts to one roughly circular.

RE: Which glue is best for robart hinges?
 

Addendum to clean up:

Just to try something different, on the next plane where I used Gorilla Glue I wanted to see if the installation could be done without wiping excess off after it expanded. On every hinge surface I used the same procedures but omitted wiping off the expanded excess with acetone. I just left it there to dry completely. The results were that there is no need to wipe off expanded excess at any time. Just lifting the tape from the surface and cutting it along the hinge line provides a clean removal. The tape takes the excess away with it, saving the effort of the wipe down and eliminating any chemical use.

You still need to wipe away any drippage that occurs when you first squirt glue in the hole and insert the hinge but after that just leave it alone until it's dry. If you apply Vaseline to the hinge knuckle prior to installing the hinge in the hole the glue cannot stick to the exposed knuckle as it expands out of the hole.