Using Pulldowns to work up to Pull-Ups/Chins
Just recently restarted linear progression. I decided to do Practical Programming because I want to eventually build up to doing Pull-Ups and Chin-Ups (kind of lofty goal considering I weigh over 300 pounds). I've seem the tutorials and read about banded chin-ups in the book, but even with the band with the highest resistance my gym has, I could only get 3/4 way up to a full chin-up.
I've used Cable Pulldowns before, but not to consistently improve my strength in the move and to work up to a clear goal of a dead hang pull-up and chin-up. In SS and PP I know it says that if you're doing 15 bodyweight pull-ups to add weight. I'm not sure if this also means that's when you add weight though (as would be my case). Anyone have some ideas of what rep schemes to use for these? Also, should it be sets across or should I increase the weight each set?
Note: I don't have an assisted pull-up/gravitron machine at my gym, so that's not an option.