Sure can. I've turned them myself, but only if they are warped. There is normally no minimum thickness marked on them, since they were never meant to be turned in the first place, but just be mindfull of the thickness as you're turning them, and use your good judgement and you SHOULD be ok. Don't go too thin, or it will warp in no time, and you will HAVE to spend the $300 for a new one. However, if it's not warped, I agree with the sandpaper thing, but a good 4 inch grinder with a cup brush attachment beforehand will make it much easier. Might even be suitable after the brush job without any sanding...