Yeah, especially when the chuck is too big to even hold the bits...
So a little tip for this is I cut three pieces of 2.5mm copper wire and use them to brace the 0.9mm bit centre in the drill chuck.
Can be a bit fidgety to get them in place but it works ;) 
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Some more work on the casings today.
Cut, shaped & slotted a 3.5mm machine screw to make a grub screw for fixing the copper pill in place.
Drilled & tapped a 3.5mm hole through the inner cores into to the copper pill, installed grub screw and levelled off.
Drilled & filed another tritium slot into the front section titanium casing.
Marked final positions of the various contact points on the outside of the copper core in red & blue ink.
The thick red line on the very end rotating switch piece shows where the internal sprung brass contact lines up.
The thick blue line on the body shows where the flashlight will be in the off position.
The thick red line on the main body shows where the direct drive/ charging mode connection is. 
The way these indicators will work is, when the two green tritium vials are lined up 
on the titanium outer shell, the light is in the off position.
When the green indicator on the rotary tail section is turned to line up with the red indicator in the body section 
, the light is in direct drive mode, or in charging mode if the head section is then disconnected and the charger port is exposed.
Other than that the tritium indicators let me know where the switch is positioned.
Nothing is fixed in place yet, still got some tidying up to do and fit LED & reflector.
Tritium vials installed in outer casing with UV setting glue & copper bezels in place.
