You can also take a look at my rolling knife sharpening deviceDiamond sharpening stone version。

Most household knife sharpeners allow you to drag the blade over a sharp edge or a grinding surface with a small diameter. Although the initial effect is good, after multiple uses, pits will start to form on the blade, much like the bumps on a dirt road, which will eventually make your blade very worn out. This rolling knife sharpener is more like a whetstone, and its flat surface can keep the blade even.

This knife sharpener is made to imitate those expensive rolling diamond or ceramic knife sharpeners, but it uses a 3"/75mm diameter sandpaper disc. You can buy discs with adhesive backing, or you can simply cut out discs from standard paper and attach them to the two ends of the knife sharpener using adhesive strips or double-sided tape. I use a 400-grit sandpaper for coarse grinding on one end of the knife sharpener, and a 600-grit sandpaper for fine finishing on the other end.

The blade holder fixes the blade at a fixed angle using three neodymium magnets with a diameter of 12mm and a thickness of 3mm. When placed flat, it maintains the blade at a 15-degree angle, but there is also an adjustment screw. Each rotation of the screw increases the angle by 2 degrees. Once you set it to the correct angle, you can roll the sharpening tool back and forth on the blade with light pressure, just as shown in the animation. Just make sure that the front edge of the blade holder is firmly pressed against the work surface, so you can get 3

The assembly of the knife sharpener is very simple: just screw the two rotating discs together through the center of the cylinder. I added wide rubber strips to the curved edge of the roller as tires to achieve a smoother feel, but it can also be used without them. For the blade holder, you just need to glue three 12mm x 3mm magnets in fixed positions and then insert the angle adjustment screws. Oh, if your plastic parts make squeaking noises, just apply a little light lubricating grease or oil to the shaft during assembly.