Here are some bits and pieces to improve the Ruixin knife sharpener kit. They include:
a stone holder: this goes on the end of the end of the sharpener arm near the pivot, keeping the stone from slipping out
spring tensioner: on my kit, the spring isn't strong enough to push against the stone
knob: hammer in the stock metal knobs, and this will make it easier to use
spacer: here I had just a simple scad file you'll need to modify for your purposes as I lost my measurements; I use a loose spacer on the rod that attaches to the sharpener arm to keep the end of the sharpener arm from bumping into a larger knife; I put a tight spacer on the vertical rod to keep the rotating assembly in place
arpruss
