It seems like once a year or so I have to repost about a product that I have found indispensable. The product is called Vibra-tite. You apply it to threads, let it dry for about 20 minutes and then assemble. The really neat thing about this product is that you can always make adjustments and after 24 hours it resets to lock in place. It is made by ND industries (formerly Nyloc Detroit) and sold world wide.(Yes Harry, even in Oz) I checked with a sales rep and it is safe to use on acrylic, phenolic and all metals.
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"