Weller Marksman 80W Soldering Iron
 

Ok ive been having a issue with the set screw coming loose that holds the tip in . What happens is when it heats up fully to 900 degress the soldering tip gets loose and screws up the heat .

So would it be a good idea to use a dab of red locktight on the set screw ? and let it dry and see if that will help .

No, the screw is loosening due to a natural process which exact name I can't recall at the moment. It is due to dissimilar metals heating and cooling at different rates. Just tighten it once in a while. My 20 year old iron the tips thread directly on the handle, the inside threads actually wear out and I need to replace tips every few years due to that.

it's pretty fun to watch people watch me soldering, tip falling off.... 30watt iron.. perfect job. : )