Quote Originally Posted by evil-frosty View Post
Can you show me the math/the how you get that +45 CL? Or am I misunderstanding something here?
Battlesmith is 5 levels long, and gets 3x CL. 5 x 3 = 15
ISF is 10 levels long, and gets 3x CL. 10 x 3 = 30

30 + 15 = 45 before your base class.

Both PrCs include the following line:

"Your effective caster level for the purpose of crafting magic arms and armor is three times your {class level.} These effective levels also stack with any other caster levels that might apply."

Thus they stack.