A regular drill press does in my mind not qualify as a sensitive drill press. Have you ever tried drilling a #64 bit in steel with your regular drill press. You know what is going to happen don't you. The bit is going to break before you really get started. Even around 1/16" you will not be able to feel the drill bit cutting. For drilling below 1/16" you need much more speed than our regular drill press can provide. So, I switch to my small drill press, about 8" swing and much finer quill feed for most drilling below 1/8". This little machine also has a much higher speed range required when drilling small diameters. Although it does have about a 3/8" or 1/2" chuck it would be useless for that size drilling in metal. Speeds start too high.
However when you add the sensitive chuck as mentioned before you now have a sensitive drill press. You no longer use the quill feed but a finger feed. The chuck has two shafts inside each other. The smaller inner shaft has a small keyway the full length and the outer shaft, the part that chucks into your drill press chuck has a small key in a slot held in by a thin spring ring half way up the shaft. This makes for a telescopic shaft. The inner shaft which is spring loaded holds the small chuck and above it rides a knurled disc with a bearing in it.
In use you hold the disc between two fingers and then you can gently pull the chuck down and then you can feel the tiny drill bit cutting.
Illustrations below.
View attachment 29823 View attachment 29822 View attachment 29824
Another kind of sensitive drill press was made by Dremel Moto Tool. It held your standard Dremel moto tool with a chuck on it. Here you raise the table via a knob operating a cam under the table giving you the same sensitivity as the chuck above did.
View attachment 29825 View attachment 29826
I hope this helps, Nick
p/s
In the previous mention of this chuck it shows a price of around $270.00. WOW. I use to sell it without the chuck for around $70.00 and a precision Jackobs chuck ran around $100.00