Wes wrote:
"John R. Carroll" wrote:

Why not cut a small thread relief and start your cut from the chuck
and move in the +Z direction?
Just flip your tool over and run the spindle in reverse.

I know what you are saying but I'm using this:


http://www.drillspot.com/products/10...ost_holder?s=1

One of these days I'm going to try your way though. Actually if I had
to make a lot of these things I'd give up on my way, grind a HSS bit
and use your way. I only have to make three more now.


You can always grind up a bit or two now or pick up the appropriate holder
cheap when you see one.
Then you'll be prepared and the pucker factor will be less.
Much less.

Personally, I'm only happy when the tool rotates and the work is clamped.
I've seen too many parts come out of big CNC VTL's when the programmer or
operator didn't clamp the table RPM.
I've also seen hydraulic chucks gradually let go as the spindle got really
turning.

Breaking an end mill happens. Crashing into a part with a tool is something
to avoid but at least when either of those happen, your work doesn't chase
you around the room trying to kill you.


--
John R. Carroll