Place one piece of wood on each side of the scraper blade, leaving the intended part of the blade exposed on one side for sharpening. The wood and blade should be flush on the other side. The wood will help stabilize the blade for sharpening.
Place the C-clamp around the two pieces of wood that have the blade in the middle and tighten the clamp until the wood is securely held together.
Lay the wood and blade with the flush side on a sturdy work space and hold the file at a 90-degree angle over the exposed blade.
Move the file in one smooth direction across the blade away from your body, and repeat until the blade is sharpened to your satisfaction.