The Channel scraper comes pre-sharpened. I suggest trying the tool as delivered on some scraps of wood before shaping the blade to your desired channel profile. This will show you how easily the tool cuts when sharpened properly.
There are many methods and techniques to sharpen a scraper. For the channel scraper blade, the cutting edge must be at 90 degrees to the length of the blade for the scraper to effectively cut in two directions. The blade is made from a HSS (High Speed Steel) hacksaw blade. Here is a sharpening method that works consistently.
1. Shape the end of the blade to the desired
channel profile at the C-bout. A pedestal grinder or a disk
sander are the tools of choice here. Avoid getting the cutting
edge too hot. (Too hot and the blade will lose it’s hardness.)
2. Flatten the sides of the blade on a stone by
moving the blade in one direction only, away from the cutting
edge. A medium Arkansas or similar oil stone is preferred for
the sharpening process. ( Note: Many water stones have a soft
bond and may round off the cutting edge.)
The burr that is left from the stoning
process is just right. I find that burnishing is not necessary
and may actually be counterproductive. I have measured the
size of the burr on scraper blades that cut well with this tool.
The burr size is less than .0005”( that is less than 1/5th of
the diameter of a human hair).
The video below demonstrates sharpening the blade
for the Channel Scraper Tool.