Hello, I want to know how I can improve my roasting so that the beans have a better expansion. When I look at some of the beans that have been roasted by others I see very nice expansion but still the crack down the middle is still nice and light and I'm wondering how they do that. While my beans tastes good, I have no complaints there, I would like to make my visual appearance a little bit better. Any tips and tricks? So far I have only roaster Central and South American coffee so maybe if I was switched to an African or something else then maybe I would notice a difference?