Hi Neville. From your opening post I assumed that you had some specific need to use the Proxxon chuck. As the thread has evolved it looks like you are planning to buy one, and I wonder why.
It may be that you are thinking that because Proxxon stuff is generally well made the 4-jaw will be a cut above the (much cheaper) Chinese/Indian offerings. That is not necessarily true. My first lathe was Proxxon PD400 which came with a really lovely Rohm 3-jaw – smooth and accurate. I ordered a 100mm 4-jaw (~£200) assuming it would be of similar quality. I received a Proxxon branded item which proved a real pain to use – very sticky with screws binding in the casting. The 4-jaw which came bundled with my Chinese lathe is far smoother. Looking at your Amazon link I see two reviews, one saying it's 'well manufactured and functions perfectly' and the other:
'The level of "precision" is just atrocious. There are no two jaws that would be of the same height. The machining is just sloppy with a lot of "apprentice marks" like burrs, uneven angles and discoloration from overheating. There is a lot of grinding dust and metal chips in the jaw screw threads. The starts of threads of the jaw screws are misshaped. The screws are binding in the head even without the jaws installed. Hopefully it all can be fixed but the chuck is absolutely not worth the money.'
My experience with the PD400 chuck wasn't as dire as that of second reviewer, but closer than that of the first.
Apologies if this isn't relevant to the decisions you are making Nevillle, just my two ha'porth (as we're going back to imperial).
Regards, Robin.
Edited By Robin Graham on 02/06/2022 23:10:28