Screw-on chuck mounting to bayonet.

[Toolmaker51]

I have the same problem type lathe, you have done a Excellent job with the conversion ,I suppose you would not nip over and do mine,Great Job.

Rofl: "Nip over...". He's either nearby or other half of the planet? He'd be certainly be a terrific visitor!

I'm jealous regarding Bayonet mount system; completely unfamiliar to me. Still shot of vid told me "aaha, converting to short taper A1 or A2."
Nope, not even close. we share no pity for threaded spindles. Not even complimentary on indexers etc. I've had a milling cutter impart enough leverage causing a chuck loosening, while climbing a transverse slot.
The bayonet carries benefits akin A1, A2, D, and L. The biggest to me, is split but accomplished simultaneously, positive drive and positive orientation. A's, Bayonet and L get that built-in with the drive boss [A's and Bayonet] or key [L's]. D requires a step you undertake personally. The cam pins impart positive drive, but there is no feature returning to same bores they are initially set for. Yet I remain D-mount fan in lathes they are appropriate, which get pretty big.
Mark the chuck plate and spindle, a paint mark is sufficient. A chuck will take a stamp, most spindles hardened beyond range a stamp can penetrate. I feel assured when each cam is marked as well, indicating engagement.

Larger machines seem to depend on retention bolts of "A", where operating the spanner for "L", or Tee handle for "D" is pure gymnastics. Same machines rarely if ever have the chuck removed, as faceplate and jaws are combined.
But that bayonet!
https://www.smalltools.com/lathe-spi...ication-chart/
It's missing from this US version chart. It may be more common for European users.