I’m not going to take credit for this simple product enhancement, only putting it into pictures. I’ve got a knife sharpener called the Edge Pro. The model I own is the APEX. It’s smaller and less expensive than the PRO model and also lacking in a few nice features. One that the PRO model has is a spring loaded stone holder that makes it very fast to remove and replace stones when wiping them down, flipping them around, or switching between stones. The APEX doesn’t, but it’s easy to modify so that it does.
Doing this is easily described as: replace brass collar with appropriately sized spring. But for as simple as that sounds, you see the question asked on knife forums, how? E.g. go here and search for the word “spring.”
In this first photo you see how the stone rectangular metal blank shown) is held. The round knob/handle is tightened onto it’s threads pushing the brass collar into the, the front stone holder (black plastic piece on the right of the metal blank) clamping the stone holder in place.
To remove the stone, you unthread the knob, relieving pressure on the collar and front stone holder, and remove the stone.
Normally, you’ll put a new stone in between the black plastic holders, re-thread the knob and move on. To speed up the process, put a compression spring in place of the brass collar. I found one at my local Ace/TruValue hardware store in the fitting aise for $1.29. The dimensions were 1-7/16″ x 7/16″ x .041. This is just a wee bit longer than the brass collar and just big enough to slip over the 5/16″ diameter rod without rattling around. If you have an option, go for something made of stainless as the sharpener will get wet if you’re using the water stones properly.
One last little problem to solve. Everytime you remove a stone, notice how in the picture above, the front stone holder will slide down the rod if it’s tipped down. This isn’t a huge problem. It just means you have to pull it back out a bit more when loading the next stone.
I reduced this effect by gluing the brass collar on the other side of the front stone holder with a dab of waterproof adhesive. This will keep it in place, but is easy to remove and won’t mar the rod. Besides acting as a stop for the stone holder, it’s a convenient place to store the part without losing it. If the spring ever fails midway through sharpening something, I can always return the brass collar to its original function rather than have to immediately run to the store to find a new spring.
Now, changing stones is done with a simple squeeze and release as shown in the clip: