try having one bot making axes and putting the axes into a storage box, then tell the wood chopper to chop 10 trees and have the bot try and pull out a new axe from the storage box where the axes are being stored. If the bot already has an axe, it will just ignore the 'grab a new axe' command and keep on chopping while if its axe broke then the bot will grab a new axe out of the storage.