locktite question

[phaed]

i was told to put locktite on all bolts that are metal to metal. i did that, but my raptor 50 has a lot of self tapping screws that go into plastic. do i or do i not put locktite on these as well? is there something else to use on them, or do they just not get any love?

thanks in advance.

[ausheli]

i usually just put a drop of CA on any screws that screw into plastic

[WayneBrown]

CA is the ticket! Use medium, or if you can find it, tire mounting CA for cars works very good.

[madcratebuilder]

ThreeBond #1401B is a metal to plastic threadlock product. I have been satisfied with it, but it's hard to find. This site has a plastic threadlock in three grades.
http://www.glue-shop.com/info4.htm

CA well crystallize some plastics.

[Ivan]

If you look at the low temp lock nuts (used on helis) they have a nylon insert. The friction of the nylon to the threads creates the locking effect.

It works the same way when you screw a self tapping screw into the nylon of the heli frame. The solvents in CA will dissolve the Nylon before it sets and usually strip the hole when you try to unscrew it, leaving a big hunk of plastic on the end of your screw.

Screwing a self tapper into nylon is self locking by design, and requires no further locking. I have never had one of them come loose. The big secret is to not over tighten them, as a ham handed installation will rip the threads out and cause the same situation as the CA.

Several people will probably argue with me avout the CA, as they always do when I post this, but if CA were needed, then the nylock nuts would be absoutely worthless, and I just don't see people putting CA on the nylock bolts. Also, three Raptors, 5 Shuttles, and a Venture have all flown without CA on the threads, and never had a screw come loose.

[flyinfool]

I agree with Ivan.
Ca can cause more problems that it will help.
The trick with plastic is that when you are rebuilding, turn the screw backwards and you will feel where the old thread starts. You want to be able to put the screw back in the same thread that was originally cut. If you let the screw cut a new thread each time it goes in it will weaken the plastic and strip out or pull out under load.

[phaed]

thanks for all the helpful tips.