Sharpening Multitool Blades
Any section of flat, unglazed ceramic or stone tile can do the job.
After dulling an oscillating-multitool blade on grout, I sharpened it with a piece of tile. I angled the bevel on the blade to lie flat on the unglazed back of the tile. After getting a feel for the angle, I turned the tool to the lowest setting and carefully brought the tile into contact. I rocked it a bit to sharpen along the curvature, and it took about 10 seconds of sharpening to refresh the whole blade. Then I unplugged the tool and removed the burr by hand by running it flush along the bottom. Since then, I’ve found that any section of flat, unglazed ceramic or stone tile works. I now keep a small piece in my multitool box.
— Connor Warneck, Royal Oak, Mich.