Spring load Y axis, anet A8, Prusa I3

i heard about spring load axis for CNC machine. so i decided to create my own version for my 3d printer.
it will decrease the vibration of the belt and keep the tension even at any moment.

the spring i use is the standard bed level spring (7MM). later i found out it will not be enough if you have a heavy bed like my. so i used a extra pen spring and if you can use a powerful spring i will recomend you to use it.
i used a long M3 screw (52MM) and its nut.