| Hole Qualities |
| Excessive re-pointing |
| |
A:Smaller hole size |
| |
Hole diameter will be below size if the margin part has disappeared. |
| |
B:Poor hole quality |
| |
Poor chip evacuation caused by a shortened flute length,
causes poor registration accuracy and roughness. |
| |
|
| Too much wearing |
| |
A:Poor hole quality |
| |
Increases contact between the drill's surface
and the inner hole, worsening accuracy, smear and nail heading. |
| |
B:Smaller hole size |
| |
Hole diameter will be below size caused by the worn drill |
| |
|
| Countermeasure |
| |
Check the margin length, the margin part and clearance at
re-pointing.
Only remove suitable amount during repoint.
(Recommended : Over 0.2mm of the margin part should remain) |
| |
|
