Depth adjustment stopper for drill bit

A depth-adjustable stopper for a drill bit, which is provided to be moved in an axial direction of the drill bit along a male thread portion formed on an outer circumferential surface of the drill bit to be able to adjust a depth of a hole drilled, the depth-adjustable stopper comprising:

• a spring configured to prevent the depth-adjustable stopper from being shaken or pushed back due to a gap of the male thread portion;
• a fastener body fastened to the drill bit while spaced apart from the depth-adjustable stopper to support a tension of the spring;
• a rotational structure body including a female thread portion formed on an inner circumferential surface thereof to be engaged with the male thread portion of the drill bit and moving in the axial direction along the male thread portion of the drill bit;
• an adjusting structure body including a through hole to allow the rotational structure body to fit thereinto and configured to freely rotate from the rotational structure body to face a material to be processed;
• and
• a bearing provided between an inner circumferential surface of the adjusting structure body and an outer circumferential surface of the rotational structure body, wherein when the rotational structure body rotates along with the drill bit, the adjusting structure body supports the material without receiving any influence from the rotation by the bearing, wherein
• spring fixing grooves are formed in respective opposite surfaces of the rotational structure body and the fastener body to support both ends of the spring.