What consequence occurs if a drill bit has a worn margin?

A worn margin on a drill bit primarily affects the bit's ability to maintain its cutting geometry and effectiveness. When the margin, the part of the drill that is supposed to prevent excessive wear and guide the bit as it cuts, becomes worn, it compromises the drill's overall performance.

In scenarios where the margin is worn, the drill bit does not maintain the correct cutting profile, which leads to inadequate material removal. This results in the drilled holes becoming undersized because the drill bit doesn't effectively cut the material as it should. Instead of removing the expected amount of material, it may only scratch or press down on it, resulting in holes that are smaller than intended.

In contrast, larger or oversized holes would generally be the result of increased wear leading to a lack of precision or clearance, but with a worn margin specifically, the hole size is more likely to remain smaller due to a lack of effective cutting action.