Has anyone used a rotary blade sharpener, and if so do they really work and are they worth the money? Could anyone recommend a good one? I have had hand and shoulder surgery so I need to use a very sharp blade at all times to ease the strain on my joints, and the cost of replacing the blades is getting very expensive. I saw an electric sharpener at a fabric store that retails for $60. CDN, but I'm not sure whether to give it a try or not. Thanks in advance.