On Wed, 21 Aug 2013 07:48:53 -0400, Joe AutoDrill
wrote:

On 8/20/2013 8:06 PM, DoN. Nichols wrote:
Just out of curiosity -- is he going to be using split-point
drills? He should, as they should reduce the thrust needed
significantly.

On larger diameter tooling, I always suggest a split point tool - or
even single step tooling at times. At this point, I'm not sure what he
has chosen though.

With ductile iron, machineability depends heavily on hardness (this
sounds like a soft casting, though) and the level of free, dispersed
carbides. Trying to get too delicate with drill bits is not likely to
give good results. Something like a Racon point may be the trick, but
I'm sure there is experience-based data on drilling the stuff, which
is a lot better than guessing.

--
Ed Huntress