@diesl
YEAH I'm not completely taking the chains durability away just saying that because of other factors in play on top of unknown factors makes it unquantifiable. The exercise machine could be mad with thick ropes that could be cut by an axe. There's also usually a wheel and a holding mechanism involved that makes it so you aren't fighting against any other forces but the weight of the object pulled. In this case is the star being pulled or is it the facilitating apparatus? How heavy is the facilitating apparatus?