One

 

 

 

 

  • Problem
    • Worn bit head
  • Probable cause
    • Typical signs of back reaming to remove the hammer from a collapsed hole
  • Corrective action
    • Improve flushing, more air
    • Use water or foam in flushing air to stabilize the hole

Two

 

 

 

 

  • Problem
    • Bit striking face damage
  • Probable cause
    • Difficult to find signs causing this damage, but most probably wrong type of tools have been used to remove the foot valve when replaced
  • Corrective action
    • Use correct tools (foot valve puller)

Three

 

 

 

 

  • Problem
    • Lost buttons
  • Probable cause
    • A lot of “free hammering” to remove a hammer that is stuck in a hole
  • Corrective action
    • More care cleaning the hole when drilling in bad rock formations

Four

 

 

 

 

  • Problem
    • Button breakage
  • Probable cause
    • Excessive wear of metal in bit body
  • Corrective action
    • Decrease flushing to reduce sand blasting
    • Change to a bit with more or bigger flushing holes
    • Regrind buttons to reduce protrusion

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