Drilling holes using a pilot hole
Drilling holes using a pilot hole
(OP)
When drilling large holes (one inch or larger), when is a pilot hole required? What size should the pilot hole be?
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Drilling holes using a pilot hole
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RE: Drilling holes using a pilot hole
Alan M. Etzkorn

Product Engineer
Nixon Tool Co.
www.nixontool.com
RE: Drilling holes using a pilot hole
Pilot should be same diameter as width of point of finish drill. Any smaller requires more HP and invites wandering; any larger increases wear on localized areas of lip and invites over feeding.
Griffy
RE: Drilling holes using a pilot hole
Radial drills would have the arm deflect away from the workpiece and at breakthrough would unload into the drill. Causing high feed rates and the possibility of chipping or breaking the drill. Smaller drills were of insufficient capacity and damage to feed mechanism or stopping the spindle has occurred.
RE: Drilling holes using a pilot hole