My plane manual says to put thread lock on screws holding servo arms in place. Should I wait to do this until my plane has been trimmed out?

Don't use threadlock on the servo arm screw if the servo gears are plastic. Only use it on metal to metal.

I wouldn't do that. Just snug them up, they'll be fine.

Agreed. Don't use threadlock on them. It should only be used on metal to metal contact. Just snug the servo screws down tight (but don't over tighten them) and you will be fine. I've never had one come out yet.

Ken

Thanks guys. This instantaneous response stuff is amazing...I love this site.

That's how we roll around here. Right Ken??!?!!

What??? Who??? When????? Huh????

Ken

if you are using metel servo's and using a gas engine i would say yes as gas engines have alot of vibration. if on a nitro engine no and with plastic splines

It's a good idea to explain WHY you shouldn't use it.

The plastic that a lot of manufacturers use is not compatable with a lot of things. Thread lock and WD-40 are two of the things I'm aware of.

A few years ago I had a can of WD-40 leak all over a transmitter. A few months later the transmitter case literally fell apart like a broken egg shell.

U sure that wasn't hot sauce from Packo's?

Hank

Along that line. A representative of Loctite came to where I work and had a 2 day class on Loctite products. (at the end of the class we all went home with plastic tool box stuffed full of enough Loctite stuff to last a life time, I will never buy threadlock again )
The threadlocker actually has a chemical reaction to metal that causes it to cure, it will not react to plastic.

One other note:

When you DO use threadlock on metal to metal connections, use a "Microbrush" to apply it.

This prevents you from overdoing it, and you get pinpoint accuracy.

One Microbrush can last through many applications.

FYI Consider Karbonite gears the same as plastic where locktite is concerned, it will attack it and make it brittle.

From the sounds of this I've 'overdone it', assuming overdoing it would mean thread lock all over my fuel tank after installing the engine mount

I cleaned it off.

Thread lock will ruin most plastics...... I used it on the bolts of the plastic front fender of my new Honda an some got on the bolt hole edges an it cracked within a day or so of that and literally fell apart in that area.

With a good snug tighten on the servo arm screws they will not come loose.


Ronnie-The Toolman

If you do use threadlocker use the Blue type. The color codes are constant among manufacturers and Blue is the type that can be removed. Red is permanent and I think green will wick into threads that are already screwed in, but from what I understand once its in there it will never come out.

Just remember BLUE

Actually, Pacer (and probably some others) make several different forumlas in the various colors. "Blue" does generally mean med strength, and generally works well. Oddly enough, last time I checked, most of the blue forumlas were recommended for bolts 1/4" and bigger. I picked up a bottle of "Purple" foruma 222 (I think) that is intended for bolts smaller than 1/4" and generally use that when I want threadlocker.

Your correct about the green. Its also great for holding bearing races on pinion gears where the hard bearing race might wear away the softer pinion.

I just got a JR Vibe in for review and it came with two bottles of thread locker, red that is medium strength and green thats permanant. Go figure. It was well annotated in the manual though.

Almost every servo arm is driven by the teeth of the servo's output shaft. There are teeth inside the servo arm that match up. There is almost no stress on the screw that holds the arm to the servo's output shaft.

The vast majority of hold down screws thread into dissimilar output shafts. They have a metal screw into a nylon shaft. Those suckers really do not need anything more than enough tightening to make sure the teeth of the arm are completely in touch with the teeth of the shaft. There won't be any forces to amount to spit that work against that screw. At least work forcefully enough that the screw would even feel them. And there won't be any vibrations that the metal to nylon grip would feel significantly.

You don't need thread lock on a servo screw UNLESS the screw is metal and the tapped hole is metal or a very rigid material. Only screw/shaft combinations that have no natural grip between them (metal to metal for instance) are going to need thread lock.

Matter of fact, a metal screw into most nylon shafts don't even need more than a finger tightening.

Want to know how much stress is on those screws most times? A buddy flew one of his favorites for over a year before he noticed that the aileron servos were missing those screws. When he saw that at the field one day, he laughed and mentioned that he'd noticed those extra screws left over from when he'd finished the plane and had wondered what they were from. So he knew he'd flown without them from day one. Still, nobody would be advised to leave them out. They do prove to you that the arm is seated adequately. And you can't rely on the arm to shaft having enough natural grip. But you don't need to strong arm the tightening if they're the combinations that don't call for thread lock.

Yeah, vibration is the killer and that is typically on metal to metal as has been mentioned several times.

Purple eh? Interesting I have never noticed a small diameter threadlocker, I will have to check that out.[8D]

In the mean time the Blue stuff is available from Loctite, Pacer or Permatex in any local Autozone or Walmart and it works great on any size bolt that is on an RC airplane.

I was gonna post much the same thing, a friend of mine put several very aerobatic flights on his cub before noticing he'd forgotten EVERY servo screw... LoL.

When I tighten that screw, I do it with the servo powered. It's tight enough when the servo buzzes a touch to hold it's position. 2 fingers on the driver do it easily.

J

Ooops, it's actually Loctite brand.

http://www.loctite.com/int_henkel/lo...id=19&layout=3

will get you to the loctite website, and you can go down through "assembly products" -> "threadlockers"....

Lots of stuff out there.

I'm not sure, but I think if you break the engine mount screws trying to remove the engine mount, you have used too much thread lock[X(]

Screws going into plastic are self locking. That's why they make Nylock nuts.

If you are flying a 4 stroke and using metal gear servos, you better use something to lock it down or they will come out, arm and all. I had it happen on two servos in one day and was lucky I had two elevator servos and the other was rudder. You don't need it on nylon gear servos, but with metal you really do. The screw will work it's way out and I checked them all at the beginning of the day. I was into my 4th flight when it did something stupid on a loop and decided to land. Didn't know I lost rudder until I tried to turn it on landing.
Ed