Fuel sender set up

I pulled my fuel tank to install a new fuel line...thought while I had the tank down I would adjust the fuel sender that never really gave me an accurate reading to begin with...I had about a gallon left in the tank so I bent the float to read E on my gauge.... I think I bent the float too far because after a couple of days it reads half and then a couple days later E....I know I have at least a half a tank still. So getting to my question.....
I am going to drop the tank again and I want to know how you all calibrate your fuel sender....
any tips would be greatly appreciated.

 

Put a tape inside and measure from the bottom of the tank to the top where the sender mounts, then bend the float wire so you have the same depth I raise the float so it'a about 1/4" above the bottom.