US Patent 10322517 Blade assembly having entrapped spring

A blade assembly for a hair cutting apparatus includes a first blade having teeth extending along a first blade edge, and a second blade having teeth extending along a second blade edge. A distance between the first and second blade edges defines a blade gap. A yoke is coupled to the second blade and configured to convert motion of a drive into reciprocation of the second blade relative to the first blade to cut hair. A spring includes a spring base and at least one spring arm configured to reciprocate with the second blade. A guide assembly includes a guide and a spring retainer, the guide being positioned between the first blade and the second blade, and the spring retainer fixing the spring base relative to the first blade, wherein in response to moving the guide relative to the first blade, the blade gap changes.