Quote Originally Posted by wmgeorge View Post
Folks he's using a CNC machine, he does not need to spot drill and it all worked fine before.
It does not matter what the machine is CNC or a manual Drill Press a Spot drill is always needed unless the Drill bit is designed to be used without a Spot Drill, there are some quality Drills that are ground so a Spot Drill is not needed, I would say he got lucky with his hole sizes before, a drill Bit unless you know how to grind it can make any size hole you want, over size or on size

Using the Drill Chuck that he has is never going to be very accurate, these drills are some of the best there are if he wants a quality drill Wedevag that will drill on size if his spindle and holder runout is very low and he would need to be using a Screw Machine Drill

North Bay Cutting Tools

Or Ebay https://www.ebay.com/itm/3906-25-64-...ss!37179!US!-1