y-axis belt tensioner/idler

Tired of having to take the whole heatbed/platform apart just to adjust the tension on the belt, I decided to make a tensioner that can be adjusted with the use of a button in the front of the printer. This is for the Graber i3 model.
The front panel needs a 3mm hole to acomodate a M3 bolt that must be glued to thebearings holder.