Earlier today, I rounded over the edges on a piece of walnut using a Bosch 1/4" roundover bit. Even though I kept the router moving, there were some burned spots. I guess I don't understand how a bit burns. The bit was brand new, so it was presumably sharp. When the bit comes into contact with the wood, why does it burn instead of just removing the wood, if that question makes any sense? Inquiring minds want to know.