Getting the 16 year olds off of machines

I try really hard to avoid going to any PF club during that afternoon rush but sometimes I have to go to the club near my job when I leave work. Every single time I go after work it’s so full of high schoolers, good for them, but it’s irritating when they have a 20 minute long conversation on the only pec fly machine in the building. I’m typically very non-confrontational by nature so I have a lot of trouble finding a way to work in with anyone. How do I find a polite way to say “dude, go have social hour somewhere else” when I have to go after work?