Why are aircraft drills sometimes sharpened with a step at the end? is
it for drilling sheet in two stages?

On 28/03/2012 11:37 PM, F Murtz wrote:
Why are aircraft drills sometimes sharpened with a step at the end? is
it for drilling sheet in two stages?

The smaller point makes the drill easier to start and less likely to
wander or slip.

--
Regards,
Noddy.

Drills for countersinking rivets are ground with the smaller extended drill
point, it keeps the countersink circle concentric with the hole for the stem
of the rivet.

--
WB
..........


"F Murtz" wrote in message
ond.com...
Why are aircraft drills sometimes sharpened with a step at the end? is it
for drilling sheet in two stages?

F Murtz fired this volley in news:nCDcr.5107$%E2.2338
@viwinnwfe01.internal.bigpond.com:

Why are aircraft drills sometimes sharpened with a step at the end? is
it for drilling sheet in two stages?

Those are specifically for sheet metal. The so-called "bullet point"
drills you can buy now are an offshoot of that.

It's almost impossible to get a large bit to center and _stay_ centered in
very thin stock.

LLoyd