Drive mechanism for a reciprocating tool

A reciprocating saw, comprising;

• a housing having at least one handle portion at a rear end of said housing;
• a drive shaft rotatably mounted in said housing;
• a motor in the housing for driving said drive shaft;
• an elongated plunger located in said housing for reciprocating motion in the lengthwise direction thereof and having a rear portion and a front end portion for attaching a cutting blade;
• an elongated guide rocker having an upper end portion with a first pivot connection to a mid portion of said plunger and a lower end portion with a second pivot connection to said housing, said first and second pivot connections maintaining an orientation of a plane of the blade substantially constant during said reciprocating motion;
• a wobble drive mechanism comprising a wobble drive shaft connected to said drive shaft, an elongated arm having a lengthwise axis extending upwardly from said wobble drive shaft, said arm having a third pivot connection to said plunger for reciprocating said plunger generally in a lengthwise direction thereof during alternating cutting and return strokes;
• a counterweight having a main portion that extends above and on opposite sides of said plunger and side portions that extend downwardly to said counterweight pivot connections;
• a support configuration associated with said counterweight and housing for supporting said counterweight while permitting reciprocating movement of said counterweight in said housing in a direction generally parallel to said plunger movement, said support configuration comprising a pair of spaced apart elongated rods oriented in a direction parallel to said lengthwise direction of said plunger and mounted in said housing, said counterweight having apertures in said side portions thereof in which said rods are inserted, said counterweight being movable relative to said rods.