Threadlocker on plastic servo arms?

[ACITceva]

Hi Guys,

I'm trying to threadlock this small M2 nut onto the bolt through my plastic servo arms and no matter what I do it seems that I get a very little seepage that ends up on the plastic under the nut.

I'm generally pretty paranoid about threadlocker on plastic but I'm not really having any luck finding a technique that avoids it. Any ideas? Should I just not worry about it?

[Ace Dude]

You could use Loctite 290 which is wicking grade designed to be used after assembly. It runs like water so I only apply a tiny drop using a toothpick at the joint between the nut and threads.

I've also used CA post assembly with good results.

The last option would be Vibra-tite VC-3 which is compatible with most plastics.

[ACITceva]

Originally Posted by Ace Dude

You could use Loctite 290 which is wicking grade designed to be used after assembly. It runs like water so I only apply a tiny drop using a toothpick at the joint between the nut and threads.

I've also used CA post assembly with good results.

The last option would be Vibra-tite VC-3 which is compatible with most plastics.

I've seen the CA idea mentioned before. Would it still be removable if I had to in the future?

[ACITceva]

Also I've been thinking that I might have better luck trying the gel style threadlocker.

[Ace Dude]

Originally Posted by ACITceva

I've seen the CA idea mentioned before. Would it still be removable if I had to in the future?

Yes.

With any product ensure it's compatible with the materials you're using.

[KSHeli]

+1 on green Loc-tite

I'd just use the green thread-locker since its a wicking styel it will get into the threads and hold.

[ACITceva]

Originally Posted by KSHeli

+1 on green Loc-tite

I'd just use the green thread-locker since its a wicking styel it will get into the threads and hold.

Honestly though the wicking is part of the problem - I'm using blue threadlocker (not loctite brand because it's a hassle to get here) and it's liquidy enough and the nut so tiny that if I apply after assembly it's still seeping through to the plastic very slightly. I think I need less wicking and not more which is why I'm thinking the gel might be better.

[KSHeli]

Originally Posted by ACITceva

Honestly though the wicking is part of the problem - I'm using blue threadlocker (not loctite brand because it's a hassle to get here) and it's liquidy enough and the nut so tiny that if I apply after assembly it's still seeping through to the plastic very slightly. I think I need less wicking and not more which is why I'm thinking the gel might be better.

Try using a small hex or a needle and only apply a very small amount inside the nut only before installed the bolt. This is the way I do it when I don't want weeping on external surfaces such as frames.
Added it doesn't take much. And go ahead and use the blue.

[ACITceva]

Originally Posted by KSHeli

Try using a small hex or a needle and only apply a very small amount inside the nut only before installed the bolt. This is the way I do it when I don't want weeping on external surfaces such as frames.
Added it doesn't take much. And go ahead and use the blue.

Crazy question (and this is an example of how anal I'm being about this): The damage done from threadlock to plastic generally happens via extended contact correct? As mentioned I had some slight weeping onto the plastic horns during numerous attempts at this last night and I immediately wiped them clean. I shouldn't have to consider those horns compromised?

[oliver1071]

It doesn't bother me at all getting it on plastic. I think most of the documentation heli related about Loctite and plastic is just directed at not trying to use it to lock threads in to plastic because it won't lock.
I haven't seen it eat away or weaken anything I've let it get on. It is in a plastic bottle when you buy it and that's fine.

[KSHeli]

Originally Posted by oliver1071

It doesn't bother me at all getting it on plastic. I think most of the documentation heli related about Loctite and plastic is just directed at not trying to use it to lock threads in to plastic because it won't lock.
I haven't seen it eat away or weaken anything I've let it get on. It is in a plastic bottle when you buy it and that's fine.

+1
Might depend upon the type of plastic, but I've never noticed a problem. OP's problem I initially read as too much and thar he didn't want visible on links. Yep, just wipe off excess and have fun. Use a lot less, on most fasteners just about 1/16th inch up on the threads is enough.

[MariaFan]

VibraTite is actually a pretty good product.
Put it on the bolt threads, let dry, assemble, fly.
Dis-assemble with no damage.

[vebbyson]

I think this is another one of the things you can worry about. But in reality has no real life problem. I'm flying a 550 that has hundreds of flights on the servo arms that's had loctite on them many times with no ill effect.

[KSHeli]

I used vibratite on my 1st Trex 700e built, but after half a dozen screws came loose I'll never use it again, pretty much Permatex or Loc-Tite only for me now.

Originally Posted by MariaFan

VibraTite is actually a pretty good product.
Put it on the bolt threads, let dry, assemble, fly.
Dis-assemble with no damage.

[Smoggie]

I discussed this directly with Loctite tech support in relation to an industrial application on nylon nuts and bolts. Their tech support said that the issue on nylon to nylon was more the fact that the loctite wouldn't cure than any problem with damaging the plastic. For plastic to plastic joints Loctite have CA based threadlockers.
Given that you have a metal to metal thread interface the standard blue Loctite will be fine.