I am about to order a pullup bar that I can do weighted pullups and chinups on. Currently I have a doorway pullup bar. What I currently do is 1 set of pullups to failure followed by one set of chinups to failure with just my bodyweight since its a doorway bar. After that I drink a protein shake, afew hours later after I get about two meals in I do the rest of my arm workout then I have another shake. This is the only day I split my workout up over afew hours, because I don't want to have my arms so tired that I can't do curls, which would be the case if I did curls right after pullups. I was wondering when I start doing weighted pullups and chinups, is one set enough and should I do pullups on my chest and back days and do chinups on my arm days? I want my arms to get bigger.