Modified jig for sharpening knives on a belt grinder

The original knife sharpening jig I had wasn’t designed for use with belt grinders or, to use a more technical term, linishers. It was designed for grinding wheels, so it could take advantage of the curvature of a wheel, and it didn’t have to be so thin. A proper knife holder would be slimmer, which would be the main difference. While the jig I had worked well with sharpening wheels, it wasn’t 100% compatible with flat sanding belts and its protruding knobs were always in the way. It could only be used on one side and couldn’t be flipped over. Although this limitation could be worked around, it was a time-consuming process and often discouraged me from sharpening knives. After selling my old sharpening wheel and upgrading to a new belt grinder, I found myself with several jigs that, with few small modifications, could still be used. These jigs are widely available from various manufacturers, including budget-friendly options from China, often costing about half the price of dedicated jigs designed specifically for belt grinders.

I began by disassembling the holder and securing the front jaw in a vice. Using my small 12-volt grinder, I ground down the lower knob mounting edge until it was flush with the surrounding surface, reducing the thickness by 2 mm. To ensure the bolt wouldn’t protrude or interfere with the sanding belt, I countersunk the hole. Fortunately, the bolt I had on hand fit perfectly for the project without needing to be shortened.

Upon closer inspection of the inside of the jig, I didn’t find anything that required modification. I removed the large plastic knob from the upper hole and decided to reuse the bolt I had taken from the lower hole, which only needed to be trimmed to the correct length. Before cutting, I placed a nut on the other side of the thread to help restore it when unscrewed after the cut. The only remaining modification involved the shank, which had already been adjusted for the previous setup i.e. the wheel. This adjustment improved the functionality by allowing the stop collar to be positioned further in. This time, I simply refined the surface that had originally been ground down with an angle grinder, touching it up with my 12-volt mini grinder and a finer sanding disc.

I tested the newly improved jig both with and without a knife to check if the angle had improved. Everything looked good – I was even able to use it with medium and small knives, which was a pleasant surprise. For very small knives, I use an additional jig that grips the knives by their handles and attaches to this jig as a sort of adapter. I have to mention that my belt grinder works in both directions, but I usually use it in reverse, with the belt moving upward. I find this setup to be safer.

These simple alterations completely transformed the jig. It finally could be used with any setup – whether with linishers or grinding wheels. The main reason I chose the belt over the wheel was speed – I could complete tasks much faster and avoid the need for water. That, in turn, has been particularly useful in freezing weather conditions (at least in theory). Truth be told, I was never good with grinding wheels, and they always felt too slow for my needs. Linishers are undoubtedly the way to go – they’re fast. The versatility and efficiency of a belt system make it a clear choice for anyone looking to streamline their sharpening and grinding jobs. It turned out that they could even be used with knife jigs designed for wheel grinders.