try changing to inches per minute instead of inches per rev. Don't forget to change it back before to IPR BEFORE you start turning again.
There is an M code to do this (for some reason M8** something come to mind) but you many not have that option. I will try to look up the M code for you when I get a chance.
We have a free Okuma Knowledgebase at DataZen Engineering (www.datazenengineering.com) website that might also help you.