Patent ID: 7374470

Claim:
An apparatus for sharpening a cutting tool having a cutting edge, said apparatus comprising: a frame having at least one guide slot; a motor having a drive shaft, said motor coupled to said frame, said drive shaft defining a drive pulley rotational axis; a drive pulley coupled to said drive shaft and rotating about said drive pulley rotational axis when said motor is activated; at least one idler pulley rotating about an idler pulley rotational axis; a support member pivotably coupled to said frame and pivoting about a support member rotational axis between an engaged position and a disengaged position, wherein said idler pulley rotational axis is fixed relative to said support member; an endless belt having an abrading surface, said endless belt trained in a path over said drive pulley and said at least one idler pulley, said endless belt rotating along said path in response to rotation of said drive pulley; and a biasing member coupled to said frame and biasing said support member toward said engaged position; wherein when said cutting edge traverses said at least one guide slot in a direction toward said endless belt, said cutting edge engages said abrading surface imparting a force on said belt to sharpen said cutting edge; wherein when said force is at and below a first threshold, said support member is in said engaged position and said belt rotates along said path at a first rotational speed; and wherein when said force increases from said first threshold toward a second threshold, said support member and biasing member respond to said force to pivot said support member from said engaged position toward said disengaged position and decrease tension in said belt such that said belt rotates along said path at a second rotational speed that is reduced from said first rotational speed.