This is a filament entrance part I made for my enclosed printer. It allows the filament to enter the top and pivot around around freely without having large open hole. I have two different options for the ball fit for you to choose from. The tighter fit one worked fine for me.
Make sure your tube doesn't fit too tightly. It can pinch against the filament if too tight. Ream it out a bit if needed. I used tape to help hold the tube in place. - I just have a short length of tubing here.
Requires a ~20mm (~13/16") diameter hole. Or just use a 3/4" bit and file it out a little.
Flip the main part over so the hex side is on the bed.
I put a small groove in one side of the ball. The reason for this is so you can get your slicer to to the retracts in this area. It prevents the seam from forming a ridge that resists free movement. I use mainly Slic3r, so there I set the seam position to rear and made sure to place this feature to the rear.