Crew was removing a oak tree and while they were chipping there was a big cracking sound in the chipper. The crew turned off the chipper and looked inside and they found a piece of metal in the chipper. The chipper was a self -fed Vermeer chipper. The chipper blades were torn up and destroyed. It is not known where the metal came from but must have been in the wood. No one was hurt. It is best to look at what is being fed in but if the metal is grown into the wood someone would not see it.