Drill Press - how much vertical play is okay? Chuck keeps falling off!

[C_Claycomb]

My drill has about 1mm (according to the scale on the feed handle), where the bit can make contact with the work, then 1mm more feed before it bottoms out and the bit is really fed into the work. Is this normal? It never caused a problem till I tried to used a new set of Fisch Forstner bits to make a desk organiser for a friend's pen/flashlight/pocket knife collection and they set up some sort of axial vibration that made the chuck fall of its B16 taper! Eight times re-seated it with a mallet before giving up and stomping off to find less infuriating work!

Now wondering whether I have a problem with my drill, a problem with the taper (which was clean, dry and free of burrs), or should be using locking compound on the taper.

Any advice?

 

[Crag the Brewer]

Should not have to hit with a mallet.

I've always just stone the taper (male) gently to clean up surfaces, by hand.

Align, then slam up by hand.

Heavy, large tapping heads can be fun....I've had them drop before

 

[C_Claycomb]

That’s kinda worrying.
I didn’t start with the mallet. I started by cleaning with solvent, going over the male taper with 1200 grit paper and more solvent, then using the feed to press chuck on (jaws retracted) against a block of wood. Only when it came loose twice after that process did I start with the mallet.
It generated some serious WTFs.
Never had a problem drilling anything before with this machine.
That it should have held without the mallet does suggest there is a problem!