Martin: Having never dismantled a chuck before I didn't realise there were three separate springs lurking within – even on this later hand drill (I haven't dismantled the MF one yet). I can see how they get lost so easily!
Anyway, I've completed the 'conversion', except for making a simple elongated bush to go in the tail-stock…
The chuck parts after turning away the gear teeth:

The parts required to convert it (the tommy bar is also re-purposed material… ground steel from a circa 2005 printer, you might notice some figures on it!!), the boss was a very rusty lump of steel that needed a purpose in life:

Soldering the chuck to the boss (I hate that weedy wire type silver solder, I always make a mess with it but I've got a yard I have to use up
) :

The pretty much finished item:

Edited By PaulR on 15/01/2017 16:02:21