Page 566 - Dormer
P. 566
GENERAL HINTS
TROUBLE SHOOTING WHEN DRILLING
PROBLEM CAUSE REMEDY
Broken or twisted tangs Bad fit between shank and socket Ensure the shank and socket are clean and free from
damage
Splitting of the web Feed too high Reduce feed to optimum rate
Insufficient initial clearance Regrind to correct specification
Excessive web thinning Regrind to correct specification
Heavy impact at point of drill Avoid impact at the point of drill. Take care with
taper shank drills when inserting/ejecting from
spindle
Worn outer corner Excessive speed Reduce speed to optimum - may be able to increase
feed
Broken outer corners Unstable component set up Reduce movement in the component
Chipped cutting lips Excessive initial clearance Regrind to correct specification
Breakage at flute run out Choking of flutes Adopt a peck/series drilling concept
drill slipping Ensure the drill is held securely in the chuck and
spindle
Spiral finish in hole Insufficient feed Increase feed
Bad positional accuracy Use a spot drill before drilling
Hole size too large Incorrect point geometry Check point geometry
Ineffective swarf clearance Adjust speed, feed and peck length to achieve more
manageable swarf
565