Before I go into how to grind the steel, let's first talk about grinding methods. We are going to be removing
steel as opposed to moving
steel which is utilized when forging. This obviously requires something that can cut steel.
The old fashioned way is using files. This works quite well but requires a lot more time and elbow grease. Typically you would file out the shape of the knife and then the bevels. Then you would use sandpaper to remove the file marks.
Many people have belt sanders in their shop/garage and will try to use these for making knife blades. However stationary belt sanders are typically used for sanding wood. The belts are typically 4 inches wide by 36 inches long and often have a round sanding disk on one side. These actually work okay for polishing steel, but they don't work well for grinding steel.
Belt Sander - $125
The most common tool used now by custom knifemakers is the belt grinder, not to be confused with the belt sander. Belt grinders can cut through metal and wood alike. The belts are often 72 inches long by 2 inches wide. There are provisions for grinding flat surfaces as well as rounded surfaces by running the belt over a large round rubber wheel. The motor horsepower is also much greater with a belt grinder with motors that are commonly 1 to 2 horsepower. By contrast the belt sanders typically have 1/3 horsepower motors.
Burr King Belt Grinder - Over $4,000
Coote Belt Grinder - $500 plus motor
A more common household item for removing metal is the stone wheel bench grinder. These come in a variety of sizes and horsepower. They do not work for finish grinding, but they are effective for the bulk removal of metal, such as grinding out the profile and the majority of the bevels.
Stone Wheel Bench Grinder - $70
A good way to start would be to purchase a stone wheel grinder and a set of files. These will always come in handy, even if you purchase a belt grinder at a later date. I made many knife blades with a stone wheel grinder, files and sandpaper before purchasing my belt grinder.