page_title: Countersink
section_title: Cross-hole countersink cutter
hierarchical_section_title: Countersink / Types / Machining / Cross-hole countersink cutter
caption_attribution_description: English: A photograph of a cross-hole deburrer or cross-hole countersink.
context_page_description: A countersink is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common use is to allow the head of a countersunk bolt, screw or rivet, when placed in the hole, to sit flush with or below the surface of the surrounding material. A countersink may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges.
  The basic geometry of a countersink inherently can be applied to the plunging applications described above and also to other milling applications. Therefore, countersinks overlap in form, function, and sometimes name with chamfering endmills. Regardless of the name given to the cutter, the surface being generated may be a conical chamfer or a beveled corner for the intersection of two planes.
context_section_description: A Dan Martin Style "zero flute" countersink is a cone-shaped tool with a cutting edge provided by a hole that goes through the side of the cone. The intersection of the hole and cone form the cutting edge on the tool. The cone is not truly symmetrical as it is essential that the cone retreats away from the cutting edge as the tool rotates providing clearance. If this does not occur the cutting edge will lack clearance and rub rather than bite into the material. This clearance is referred to as cutting relief.
  These tools are best used as deburring tools, where the burr from a previous machining operation needs to be removed for cosmetic and safety reasons, however they may be used in softer materials (such as wood or plastic) to create a countersunk hole for a screw.
caption: Side and end view of a Weldon style "zero flute" countersink
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