This is a remix of the Photograaf16's Y-Belt tensioner. I had to change some dimension because it didn't fit my Anet A8 holes but the design is the same.
A want to thank him.
The four Y axis belt tensioner holes of my Anet A8 (late 2016):
Hole width: X:8.2mm, Z:7.7mm
Space between holes: X:8mm, Z:11.5mm
Print using the same configuration of the original design.
I suggest to print also the "Belt Pulley Insert", it takes just 2 minutes to print:
www.thingiverse.com/thing:2081443