Thank you for your kind words
OK, so here is the story....
I'm pre-cutting wheels in a few diameters to be used as knobs for jigs.
I cut them with Hole Saw that leaves the 1/4" hole at the center. I don't use them immediately but only when I need them for a jig.
But, I don't know which T-nut or bolt size I will be using...sometimes it's 1/4", sometimes 5/16" or 3/8".
When it comes to actual, sometimes I have to enlarge the 1/4" hole to 5/16", 3/8" or other for the T-Nut to go in and I have to drill a larger hole...not all the way but, just for the T-nut to sink in.
So, I'm talking about a situation that the small hole is already drilled and I want to drill Larger hole all the way and even more larger hole half way...and I still want them both at the center...so, I have to change drills from the 1/4", that is used to locate the center and clamp the wheel to the DP table...
After the wheel is clamped to the table, I have to change to larger dia drill that is usually also longer drill bit and I must move the DP table down (or up) but still come back and lock it at the same point.