Intriguing!

I have a couple questions.
It seems like a lot of travel just to get a soldering iron in place. Why?
I initially thought the brass knob was some sort of y-axis adjustment, but it appears, with further study, just to be a locking mechanism. Is that necessary?

Is this is an adaptation of another tool to this application and the travel and locking mechanism are not really necessary?

Thanks.

KH