I’m pretty happy with my 2418 mini CNC mill, it worked well and didn’t need any calibrating. It seems to be within about 0.5mm straight out of the box, impressive for something that only costs a few hundies. However, the most obvious improvement is reducing the amount of backlash or ‘webble wobbles’ out of the leadscrew. The ball-nut had a very loose fit and wriggles around before transferring power and moving the sliding components.

I used a washer to pack out the space between the 3D printed housing and the ball-nut. Adding a drop of superglue to the washer to help hold it in place. Even before measuring, there was a visible improvement - the carriages started to moving immediately. Now everything moves to within 0.03mm. Not a bad improvement cobbled together out of stuff I had lazing about.

Animation of the ball-nut wobbling around and not transferring power on a 2418 CNC mill
Animation of the of a 2418 CNC mill transferring power without backlash.