Hammer dirll

A method of altering the performance characteristics of a hammer comprising:

• a body;
• a cylinder mounted within the body;
• a motor mounted within the body having an output spindle;
• a tool holder mounted on the body, the tool holder being capable of holding a cutting tool;
• and
• a hammer mechanism comprising:
• a piston slideably mounted within the cylinder;
• a reciprocating drive mechanism mounted within the body which, when the motor is activated, converts the rotary movement of the spindle of the motor into a reciprocating movement of the piston within the body;
• a ram slideably mounted within the cylinder forward of the piston, the ram being reciprocatingly driven by the reciprocating movement of the piston via an air spring to repetitively strike a cutting tool when held by the tool holder, the hammer mechanism performing one hammer cycle each time the ram strikes a cutting tool during normal use;
• and
• an air replenishment mechanism which is capable of refreshing the air spring during certain time periods within the hammer cycle during normal use;
• wherein the method comprises the steps of adjusting the air replenishment mechanism so that it refreshes the air spring during different time periods within the hammer cycle and/or allows different volumes of air into or out of the air spring during the refreshment time periods to provide the most ideal performance characteristic for the hardness of material intended to be cut by the hammer.