Ender 3 Bed Leveling Lock Knob

This is a very basic knob which is designed to thread onto the same rods as the stock bed adjustment knobs on the Ender 3 and Ender 3 Pro. They are intended as lock knobs which are tightened against the stock knob to prevent it from backing out with the vibration of printing. I had a bad failure which resulted in damage to my Ender 3 Pro because the knobs backed out during a print, and these seem to have completely fixed the problem. I haven't had to re-level the bed in over 50 hours of printing.

The ID is sized at 3.242mm, which is the minimum minor diameter for M4x0.7 thread. A basic tap should work, either with a T-handle or drill, just go slowly. Make sure you have 3 or 4 walls on the ID so there is plenty of material left when tapping is complete.