16 replies to this topic

[Captain Mainwaring]

Are they not normally a nyloc version of a set screw with a small nylon 'slug' set into the thread?

My experience of those is that they fail when they get hot.

[Ethel]

The blue patches you see on some threads are encapsulated "loctite" ( the same concept as all that Laboratoir Garnier malarky), tightening the thread bursts the capsules & releases the thread lock. You certainly find it on caliper mounting bolts, dunno about the bolts in question here. It will have a maximum operating temperature, but it will surely need a significant safety margin  to be selected for any application. More importantly to us as end users, it only works once, so you ought to replace the bolt if you undo it - or at least apply some more loctite.