Why electric grinders are terrible knife sharpening tools.

The main issue is that electric grinders tend to overheat the blade, which can ruin its temper and destroy the knife’s ability to hold an edge. They also remove a lot of material, often much more than necessary, which can drastically alter the knife’s shape. As a result, many mobile services that rely on electric grinders are often dubbed “knife butchers” by enthusiasts—and with good reason. The finish is typically rough and uneven, and the process can easily leave scratches on the bolster or sides of your knife, rather than creating a clean, sharp edge.

In contrast, whetstone sharpening involves a carefully planned progression from coarse to finer grits to achieve a precise, razor-sharp edge. Most electric grinding services, however, don’t follow any kind of grit progression. They usually use a coarse 80-grit wheel for everything, which results in a jagged, uncomfortable edge that's often just as dull—if not worse—than when you started. The biggest difference? A significant portion of your knife has been ground away, often turning into dust and sparks.

While the individuals using electric grinders aren't necessarily unskilled, this method is, on the whole, one of the least effective ways to sharpen a kitchen knife. It’s especially detrimental to single-bevel knives, which require precision and care. If you need to get your knives professionally sharpened, it’s critical to avoid services that use bench grinders for kitchen knives. These tools can easily destroy the fine geometry of single-bevel edges and cause irreversible damage.

If you're unable to sharpen your knives at home and can’t find a sharpening service that uses whetstones, there are still ways to minimize the risk. First, ensure they cool the blade with water during sharpening to prevent overheating. You can also test the service with a less-expensive knife to gauge the quality of their work before entrusting them with your prized blades. When speaking with them, ask questions about edge geometry, heat treatment, and knife care—if they can provide knowledgeable answers, it’s a good sign they understand the craft. If they can’t, it’s best to look elsewhere.

Remember, there's a big difference between grinding and sharpening, and knowing how each process affects your knives will help you make the best decision for their care.