Finally got my mini lathe and now i'm looking at for my first engine to build. I first thought maybe a full working scale model of a V12 Rolls Royce engine but after much thought I settled on Elmers Wobbler no.25. I've got the plans (http://www.john-tom.com/ElmersEngines/25_26_WobblerBoiler.pdf) and i've started to convert the measurements to metric. What I am a little unsure of is what the little letters in the circle mean? I'm guessing the "P" means press fit i.e a tight fit that will not spin. But what about the rest C,S,F, and B.