I only have money for a cheap bench grinder for now. I was out looking and there were 2 I saw at a low enough price. 1 has a single 120 grit stone that is approx. 1 1/2" wide. The other has 2 stones - 36 grit and 60 grit - that are each about 3/4" wide. I can buy other stones (coarser or finer) for either one. So ,my question is - what grit is correct for sharpening mower blades? What grit stones are you guys using. Please don't recommend other, more expensive options. I know there are better machines to do it, but this is all I can afford right now. Next year, I will upgrade.