At initial position the pink pin is automatically set skewed. Its tip contacts the hammer (in blue) on the hammer face, slightly offset to the hammer hole.
When the tool body moves down, the hammer stays immobile and bears increasing force from red spring until the pink pin is pushed into alignment with center axis of the tool (when the pin tapered portion contacts narrow hole of the tool body). The hammer then can be launched down and strikes a blow on the pin to press the green punch on the workpiece.
There are several ways to make the pin skewed at initial position. Here the bottom face of the pin is made not perpendicular to the pin axis.