On Thu, 28 Aug 2008 16:57:25 -0500, F. George McDuffee
wrote:

On Thu, 28 Aug 2008 14:33:07 -0700, BottleBob
wrote:

Unka George:

For those who may not be aware of the different drill points. Example
of Bickford point below, see figure 8. BTW, that's essentially the
type of point our Darex drill sharpener puts on drills.
snip

If so, what is your guesstimate
of cycle time saved?

The chip to chip tool change time can vary greatly from machine to
machine. Of course the cycle time saving can be significant for
multiple parts or multiple holes.
========
Again, thanks for the references and hard data.

Time for a survey. How many of the group's money players
routinely skip the spot/center drill step with today's rigid CNC
machines?

What else are we doing that is a carryover from the overhead
shaft babbitt bearing machines in the blacksmith's shop?


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).
I almost never use center drills, but instead use split point drills
if I don't want or need a small edge break. Hole location is very
good. I do center drill when cross drilling round stock. Often when
the hole is to be form tapped I will use a center drill in order to
have a broken edge after the hole is tapped.
Eric