Uploaded a shorter version, since it makes no sense that the "U" part is so long.
This version requires a slightly longer Y belt.
Removed most of the play along Z in Y Tensioner Case. The other two pieces remain the same.
This is a different Y belt tensioner for AM8 frame. Works with the original Y stepper mount, so it is fully compatible with stock AM8 by pheneeny.
I made myself this one, which is more rigid and has almost no play around Z axis, it just lets move back and forth, unlike many tensioners based on two bolts and/or two sections.
It should have approx 5mm stroke, which is more than enough to give the belt that last bit of tension. Should work with toothed idler mod. Added a cutaway view to see the assembly more clearly.
-M4x24mm hex bolt
-5 or 6mm diameter (20-25mm long spring)
-M3x24mm allen bolt
-M3 washers (optional, but highly recommendable between moving and stationary parts, and also between bolts/nuts and 3d printed parts)