Re: Center Drilling

On Wed, 31 Jan 2007 13:35:41 -0500, Beege <hah@xxxxxxxxxxx> wrote:

Hi everyone.

Just curious how many use them for starting drilled holes (on parts that
don't need to be held in centers). Does the NC spotting drill work
better? And what point angle, if so?

Beege

For tool room work, I use center drills most of the time. On my Swiss
automatics and CNC's I use spotting drills, exclusively. The angle
depends on what I need, but in most cases I make them with a 90 degree
included angle, and then blunt the tip with a 120 degree included
angle to keep them from chipping, making sure that OD of said 120
angle is smaller then the OD of the drill that follows.

Matt
.