Contact screw: The closer the position of the contact point is to the tip of the front shrapnel, the slower the frequency and the greater the force, and vice versa. The tighter the contact screw is pressed, the lower the force and the faster the frequency. It is recommended that the contact screw be moved forward as far as possible, and touch the shrapnel, and then turn it down one or two turns at most, so that the shrapnel exerts its maximum power.
