Hi all, Im wanting to do some casting of non ferious metals, brass, copper, bronze, alum ect. Dont worry I have been trained in school on foundry work. Full year class of it so I know what im doing with saftey and what not. But in school we used a gas power big foundry. Im just wanting to do some small bars. My firepot in my forge is i 8" deep. what size of crucible can i pull off? Will get pics asap

Probably not very large, maybe a B4 or 6 at most, and you are going to have some difficulty getting the larger one up to temp if it's full. You want a couple inches of fuel surrounding the crucible at all times. If you've been doing your research, make yourself a small popcorn-tin furnace to do your melts, it will just be that much more efficient, both time and fuel wise. Where you want to use solid fuel, the refractory liner isn't as important, so you can get away with cheaper materials. If you are a good scrounger, you should be able to set one up for near nothing.
If you are intent on using your forge, you can have nearly the same effect by building up the height of the fire by making a chimney arrangement with firebricks, this will give near-furnace performance while allowing you to easily return it to a forge.