Tango, some people are sharpening challenged. Probably most people. The only reason I got a belt sander was to do machetes quickly. Once I gained some skill and confidence, I used it on other more expensive knives, and I still mess up sometimes. The techniques are the same whether by hand or power. Yes, you can ruin an edge if you overheat the steel. Yes, you can get cuts and abrasions if you don't pay attention. There have been some videos done on using the belt sander, but I don't remember who did them. A good sharp edge can be done with the Lansky sharpening system. Or if you want power, look at PoP's sharpener. He uses it on his fine custom knives. Don't worry about whether it is convex or bevel, sharp is sharp. Unless you are doing a lot of reprofiling or machetes and axes, you don't need a belt sander. If you do decide to get one, practice on cheap knives first.