In article
,
JIMMIE wrote:

I have a few left handed drill bits. I use thes exclusively for
extracting broken bolts. I was wondering if this is the only purpose
for which they were intended.

Jimmie

No, we used to use them frequently on the old Brown and Sharpe screw
machines. Those were the original automatic lathes, originally developed
around the turn of the century (not the most recent one!) for, uh,
making screws.

On a lathe, the spindle turns the stock, and the drill is fixed - it
doesn't rotate. So if you have an operation where you want or need the
spindle rotating backwards, you need a backwards (left-handed) drill.