The dual thumbscrew Soft-Grip Clamp was designed specifically for those looking for an easier to use clamp, that would also prevent scratching on coated or highly polished blades. Not for use on blades 1/2" wide or less.
For sharpening blades 1/2" wide or less (such as tiny swiss army-type blades), use the Standard Knife Clamp.
Loosen the front red thumbscrew screw 2-3 turns. Tighten the back red thumb screw until it is approximately one full turn from being fully tightened. Loosen the front red thumbscrew of the knife clamp again to accommodate thickness of blade. Attach the clamp to the spine of the knife blade at the center of the blade. Approximately ½ inch of the blade should extend from the end of the clamp. Tighten the front screw again to hold the knife securely. Lock the blade in place by hand tightening the back red thumb screw on the clamp.