The diameter of the drilling device is worn out, and the outside diameter of the inner whorl is expanded larger than the following table, and shall be scrapped
Specifications（MM）： 121 159 165 197 203
OD Wear（mm）: 3.17 4.76 4.76 6.35 9.33
Outer diameter expansion of internal thread（mm）: 1 1.2 1.2 1.5 1.5
When the axial bending deformation of the drilling hammer exceeds the 1.5°, it should be scrapped.
When the depth of the outer cylinder of the drilling hammer exceeds 2mm, it should be scrapped.
The body and mandrel of the drilling shock can no longer be repaired and should be scrapped.