Where to use thread lock?

[Mooncatt]

As the title says, what are the critical screws that should have thread lock used on them?

[Ron_R]

Any screw that goes into anything that is metal.

[Steve Joblin]

Yep.... all metal screws going into metal should be threadlocked. Threadlocked screws will resist backing out and becoming loose from the constant vibrations caused by the motor, gears, and flying.

[SentientPhil]

Does this apply to nuts too? How about NyLoc?

I only ask because I was bought a Kyosho Concept 30 (I don't even know how to fly ANYTHING yet either :S) and rebuilt most of it, the manual said to apply thread-lock to the nuts/bolts on the head, and I didn't know if this applies to more modern helicopters, especially if they have NyLoc nuts.

[wrench567]

Only if you reuse the nylock nuts, Once there are threads cut into the nylon from the screws being backed out they become less effective. Either new nylocks or a mild loctight will do.
Pete

[Ron_R]

If you use loctite on any plastic or nylon parts, it *could* erode the plastic/nylon causing it to fail.

[Steve Joblin]

Originally Posted by Ron_R

If you use loctite on any plastic or nylon parts, it *could* erode the plastic/nylon causing it to fail.

I have done a fair bit of research on this...

Indeed, you do NOT use both Threadlock and Locknuts... choose one or the other.

A nylon insert will be effective for a few install and remove cycles. Loctite is one-shot. So if it's a part the needs to be removed for maintenance, or adjusted (like the bolts used for attaching main or tail blades to the grips, use, use locknuts.

[SentientPhil]

Thanks all, those were my suspicions also.

I was always taught that Nyloc's were evil, something to do with excess translational and rotational force, so you can only use the Nyloc and the bolt once anyway. So the argument was 'why not just Lock-Tite them instead of Nyloc'ing them'.

Personally, I don't see this applying to steel bolts, Nyloc's aren't that stressful. But each to their own!

[wrench567]

Originally Posted by Ron_R

If you use loctite on any plastic or nylon parts, it *could* erode the plastic/nylon causing it to fail.

As a heavy equipment and big truck mechanic I use locktight products everyday. Every nut and bolt assembly on our screening plants either use a nylock or torsional type lock nut. Torsional nuts tend to seize on the threads and end up ruining bolts that need to be reused. Nylocks (grade 8) are preferred. After reusing the nylocks as little as one or two times the nylon has threads cut into it from the bolts. If I can thread the nylock on the bolt by hand past the nylon I use red high strength locktight on them with excellent results. Screening plants are designed to vibrate. Loose hardware will cause catastrophic failures to expensive parts and may cause injury or death to the operators. The bottle that locktight comes in is nylon plastic. Tell me again how locktight will harm nylon? Maybe you should contact Locktight and let them know.
For the tiny little screws and nuts for our little Helis I would use the lightest (yellow or green) over the blue and never the red. Some day you will want to remove said fastener without stripping out the head or twisting off the threads in that blind hole. The yellow threadlock is used dry. A dab on the threads and allowed to dry before use should be fine with proper torque.
Pete

[Ron_R]

There is a loctite formula for plastic components. As per this guide:

http://www.henkelna.com/adhesives/ch...cker-14075.htm

I appreciate your info, but the sarcasm? Not so much. Obviously you have more experience than I do with this, so I will defer to your expertise.

Just btw, Blade was a little overzealous with their loctite application too close to plastic servo tabs on the Blade 180 CFX. This caused the tabs to become brittle and crack. Sometimes, mid flight. Not good.

[Ron_R]

Originally Posted by wrench567

The bottle that locktight comes in is nylon plastic. Tell me again how locktight will harm nylon? Maybe you should contact Locktight and let them know.

Sarcasm above, btw. I'm no expert, just 25 years working with RC Cars and now Helis. One of the reasons I said *could* in my post.

[wrench567]

I apologize Ron.
The hardening of the plastic servos could not be the locktight but perhaps some type of petroleum lubricant. Plastic compatible lubes are available but rather more expensive than petroleum based products.
Another problem with using too much locktight would be the displacement of the product when disturbed such as loosening the fastener. the dried locktight is usually harder than the plastics used for hobby items. I have seen blue locktight crack aluminum housings when removing fasteners. One drop is more than enough and those tiny 00 size screws should only have a dab of it. I have seen guys dip 5/8 inch bolts in the stuff and run into a nightmare when it was time to remove it.
Once again, I apologize.
Pete

[SentientPhil]

It's great to see a wealth of experience on these forums!

I know this is probably beyond "RC Helicopter/car" realms and a bit OTT, but the theory should be fairly relative?

The Junkers' machine shows some fairly interesting results for Nyloc's. The nylon/plastic insert on them appears to have little effect towards keeping things tight/highly torqued when subjected to vibration/translational forces, but does do an excellent job at stopping it falling off the bolt (never a bad thing!). Nord-Lock type washers seem to have an excellent ability at keeping things tight/highly torqued under the same situations as above. We used to do something similar on our machines and never really understood why until now. I wonder how well these two would go together in the RC world?

I know the Nord-Locks would have to be mated between hard enough materials to create enough force against the nut when at optimum torque, but it sounds like a winning combo to me without having to rely on either weaker loc-tite or Nyloc's alone for the more serviceable parts. I'm not sure if this would even be an issue on RC helicopters, but thought I would ask anyway; like mentioned in previous posts, loc-tite isn't the most user friendly substance to use on serviceable parts, not with having to clean and prep before each application as well...

[Mooncatt]

Good info and thanks for the Nyloc clarification too. I'll have to change up my repair plan a bit for that, but no worries on that front.

[Ron_R]

Originally Posted by wrench567

I apologize Ron.

It's cool. No worries!