Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

There must be at least a hundred ways, some better some not, depending on situation.

Bored and soldered is about as simple as it gets, or with a wrist pin, at the other end of the spectrum, with various threaded strategies found in between. As long as you hit a reasonable mean for length, adjustability really shouldn't be too critical on our toy engines, and should be unnecessary by dimension and design on a truly engineered model.