For Example: Say I want a 1/4" hole centered in 1/2" bar stock. I secure a piece of scrap material (plastic, wood, metal, whatever...) in my vise & clamp my vise down. Then I would drill a 1/2" hole into the scrap. Remove the 1/2" drill bit, but don't move anything else, place my 1/2" bar in the hole from above if short or from below if longer. This will center the 1/2" bar directly under my chuck. Now you can place your drill bits into the chuck to step up to the desired hole
This is just the only way I figured out how to do it, but I have formal shop training, so if this is a bad way, would someone PLEASE let me Farrow. I can use all the guidance I can get.
Tight Groups, Brent
AA S410 SL Extra FAC .117 Thumbhole
Have some S410 vids at