It would be very hard to sharpen the teeth of a microplane with conventional sharpening equipment. The microplane was designed as a wood rasp--to be fixed into a hacksaw fame and shape hard wood like oak, maple, etc. Ther are versions that are round and meant to be fixed into a drill press to smooth compound curves. It was a CDN tool company, Lee Valley that brought about the idea to use the rasp for food items (and as well to sell more microplanes.....)
In my kitchen, I have the same microplane for 8 years now--citrus zest, cheese, spices like nutmeg (which produces nutmeg sawdust, if you really think about it...) etc. and it still remains sharp. In my garage I have another microplane fo shaping wood, and it is holding out just fine-except for one corner where I "acidentally" took the corner off of a steel screw.
