A simple, adjustable belt tensioner + a belt tie to replace the cable tie.
The tensioner requires an M3 screw. The screw hole is tight-fit and should provide more than enough tension to hold the screw. Designed to be printed at 100% scale.
sketchup/fusion360 file is attached in case adjustment is needed.
(Used on and printed with my Tevo Tarantula. Mine is printed at 20% infill, but use higher wall line count (shells) or high infill for maximum strength. )
Update 10/23: increased thickness for screw holder and legs. Picture is of old version.