Trouble

 Possible Cause

 How to do

Drill Breaks

 Spring or back lash in press or work
 Too little lip relief
 Speed too low in proportion to the 

 feed
 Dull drill
 Improper chip clearing

Test press and work for rigidity and alignment
Regrind properly
Increase speed or decrease feed
Sharpen drill
Correct application

Outer Corner
Breakdown

Material being drilled has hard spots,
scale or sand inclusion
Too much speed
Improper cutting compound

 Correct application
 Reduce speed
 Use proper cutting compound

Drill Breaks in Brass or Wood

Chips clog up flutes

Increase speed
Use drills designed for these materials

Cutting Lips Chipped

Too much feed
Too much lip relief

Reduce feed
Regrind property

Cracking or Checking
in Cutting Edges

Heated and cooled too quickly while
grinding or while drilling
Too much feed

Warm slowly before using
Do not throw cold water on hot drill
while grinding or drilling
Reduce feed

Hole Too Large

Unequal angle or length of the cutting
edges or both loose spindle

Regrind properly
Test spindle for rigidity

Only One Lip Cutting
Drill Splits Up Center

Unequal length or angle of cutting lips or both
Too little lip relief
Too much feed

Regrind drill properly
Regrind with proper relief
Reduce feed

Rough Hole

Rough Hole
Dull or improperly ground drill
Lack of lubricant or wrong lubricant improper set-up
Too much feed

Regrind properly
Lubricate or change lubricant
Check set-up
Reduce feed