The key to splitting a brunescent cataract is to access the central endo-nucleus. This is the densest part of the cataract and a chop created here can be propagated to allow complete cracking and creation of two hemi-nuclear pieces. This video is from Dr. Cristos Ifantides from Denver, Colorado, USA and he has a method of nucleus division that works well in these dense cataracts.
He coins this technique the rotary chop since it is reminiscent of the old rotary telephones. It involves creating a half-depth hole in the nucleus, just inside of the phaco incision. The nucleus is then rotated 180 degrees and the phaco probe in embedded again in the sub-incisional nucleus. The chopper is placed in the original hole which allows for a firm grip of the nucleus which is now trapped between the phaco tip and the chopper tip. The two instruments are brought together, through the dense endo-nucleus, and the chop is completed.
Click below to learn this technique of Rotary Chop:
Is that in chop mode when you are drilling these holes or in sculpt mode?