I bought this Dremel perhaps 5 years ago, under the thought that I should sharpen my lawnmower's blade myself. We, like lots of good intentions, that got shelved and I had the local hardware store send it out for sharpening. The Dremel has been stored, completely unused ever, in a snap top Rubbermaid storage bin, in our climate controlled basement. So low humidity (run a dehumidifier all summer) and always temperate (55º to 72º F).