The multiplier method, even if not perfect, is fine for small conduit or stuff thats hidden. You can usually get it close enough to make it work. If you have to be acurate, the best way to bend offsets is to field bend it. Field bending is described in a some books. I have an Uglys book and it is described under "Chicago Type Bender Off-Sets" This method can be used for foot benders and hydraulic ones.
