I will add > If you think that a dab of a thread lock solution would be a better thread lock than the silicone - DON'T DO IT.
The reason that you use silicone as a thread lock is that any kind of a "LOCK-TITE" thread lock will do bad things to the plexiglas material.
I havn't had to learn this the hard way, but someone I know did and I've seen more than one post that warns against using any kind of lock-tite anywhere near plexiglas.
Just a reminder.