Hinges

Fold the hinge and dip the hinge line into heated petroleum jelly, then work the hinge a few times to lubricate it...

If these are NYLON hinges I would not use CA to glue them. Use 30 min epoxy after roughing the tabs and drilling anchor holes if none are present.

Also, ALWAYS(!!) pin nylon hinges after installation....

Cheers,

Pin the hinges - I need help understanding what this means. Do you pin fabric hinges as well?

Cheers - LeeH

"Also, ALWAYS(!!) pin nylon hinges after installation" - Unable to agree 100% in this instance. In most models, the use of pins or the thick round toothpicks seen many times is not required = IF one has carefully spread epoxy throughout the hinge slot and covered the Nylon hinge tab on both sides with epoxy so that epoxy fills the holes "after roughing the tabs and drilling anchor holes if none are present". ( pins maybe desirable on models with high stress on the control surfaces, e.g warbirds and racers) The epoxy will set through the hinges like an "I" beams and not weaken the structure. Nylon hinges epoxied in this manner are not known to have pulled out - only those where builder had pushed the glue into the slot and then the hinge which simply pushed the glue into the wing with little remaining to adhere to and through the hinge itself. If repairs should be required at a later date, then a hot knife blade will clean the old hinge and epoxy out with ease. A pin or similar may be difficult to extract without causing damage to the surrounding wood which must then be replaced with new wood.

Lee:

Hinges made out of any material( fabric, plastic , CA, nylon, or whatever) can be pinned. All this means is drilling a hole and putting a toothpick or a pin in it. If the CA or epoxy has been applied properly, this is probably unnecessary considering the control surface is held on by more than one hinge. It's very unlikely they would all fail at once. However, during very hard use, like my planes, hinges can loosen up. With CA, you just add another drop or two. Epoxy is another story and is sometimes difficult to repair.

Ciao,

Mr Akimoto

First, don't use CA with pinned hinges. Use epoxy. Smear some petroleum jelly along the hinge to keep the glue out of the hinge.

Morris

Thanks

How often do hinges actually fail. I have yet to see it

Mike

What are those anchor holes used for (As opposed to pins)? Do you mean holes in the tabs themselves to increase the strength of the glue joint?

I used to do this, and hated it. It was a messy, finicky pain in the ... I would always end up with petroleum jelly getting onto the flat surface (thus compromising the epoxy bond), epoxy everywhere, and how do you get the epoxy gooped tab in the slot when its free to rotate as you hold the other piece ... Also, if you had enough epoxy for a good bond, then some would squeeze out, forming a shoulder that has to be removed later ....

AAAAARRRRRRGGGGGGHHHHHHHHH !!!!!!!!

(can you tell I hated hinging ?)

I eventually came up with a faster, cleaner, better way.

Cut slots as normal, perhaps a bit "thin" so you get a nice tight fit. Roughen tabs as normal. Slide dry hinges into place and align ... BEFORE GLUING, drill hole for toothpick pin through balsa and hinge. Cut pin to size and install dry with hinge in place (still no glue) Check to make sure alignment is still perfect. Drip a couple of drops of THIN CA onto the toothpick ... When no more CA will wick into the pin/hole, blot excess w/ tissue Flip surface over, and drip onto bottom of toothpick.

The CA would wick down alongside the toothpick, and then spread out inside the slot. Because it was not applied near the front none would get into the hinge-pin.

When I first thought to try this I was worried about strength ... I wasn't sure CA would be strong enough with nylon... So I did some destructive testing :) I know what you're thinking , but NO, I did NOT intentionaly crash airplanes ... I made little trailing edges with some scrap wood ...

The first couple test pieces the wood would break before the hinge pulled out. ... So I got some thicker harder balsa or light ply (I forget) and ran test series number 2. The wood was now stronger and did not break ... the hinge did NOT pull out ... the metal pin holding the 2 halves of the hinge together would bend and/or pull through the plastic. In other words, the wood to hinge bond was stronger than the hinge itself.

That was my standard method for many years until I found something even better ... Robart Hinge points ...

MUCH NICER than flat hinges ... no slots to make ... Just drill a (Slightly Undersize) hole in each surface. Put a couple drops Titebond wood glue in each hole. Insert hinges. (if enough glue was used, some excess WILL squeeze out) Let dry.

The Titebond doesn't really stick to the Robart plastic all that well, so the excess that squeezed out (and all over the hinge pin) will simply flake off !!!

But ... But ... But ... If the glue don't stick ... ... WHATS HOLDING THE HINGE IN !?!?!?!?

Magic ???

The shape of the Robart Hinge Points ...

They have little saw-tooth ridges on them. The moisture in the Titebond expands the wood fibers, and the wood and dried Titebond form anti-ridges that lock in the Robart Hinge Points.

Destructive testing was again performed ... the bond was again stronger than the hinge itself. Heck, with a properly sized hole it can be tough to get the little buggers out after alignment tests -- even though no glue was used yet.

Martin Bakalorz

As a final note, Alan T. suggested not pinning in case repairs are needed ... Has this ever been an issue for anyone reading ?

I have had to repair/replace a CA type hinge that wore out, (to be fair the alignment was messed up and thus higher stress) but I have NEVER had to replace pin type hinges. And if one surface got messed up enough to require replacement, I was able to cut it off the hinges and reuse the existing hinges.

I also did have hinges that were installed as well as I could (using epoxy but no pins) pull out before. I got severe flutter on a trainer/floater, and both ailerons pulled out ... luckily it had enough dihedral to be able to land using rudder & elevator. That convinced me to pin them from then on.

I'm certainly not suggesting that anyone NOT pin their hinges , cause it's a 'good thing '.....but I have never had a failure and I never pin them. I've been using the CA hinges for close to 20 years. The first ones I ever bought were called Radio South Pro hinges as I recall. I now buy an 8x10 sheet and cut out what I need. My opinion is that many people put too much glue on the hinges and make them brittle at the hinge line. Just my opinion.

Ken Day