Stepless variable-amplitude transmission mechanism and fascia gun

The invention discloses a stepless variable-amplitude transmission mechanism in the field of fascia guns, which comprises a crank-slider mechanism formed by sequentially hinging a crank, a connecting rod and a slider, and further comprises an angle adjusting mechanism, and the angle adjusting mechanism comprises a crank fixing piece and a slider guide piece which are mutually hinged; a hinge shaft of the crank fixing piece and the sliding block guiding piece is parallel to but not coaxial with the axis of the rotation center of the crank, the rotation center of the crank is fixed to the crank fixing piece, and the sliding block is arranged on the sliding block guiding piece in a sliding mode. The angle adjusting mechanism is additionally arranged on the basis of a traditional centering crank sliding block mechanism, the angle adjusting mechanism is used for changing the distance from the rotation center of the crank to the guide path center line of the sliding block, and the offset crank sliding block mechani