Problem
The Standard lathe chuck fitted is a 3 jaw 100 mm or 4 inch chuck, this has a small internal diameter capacity and not suitable for larger billets of greater than 30 mm diameter and length 100 mm. These were clamped protruding out of the chuck jaws, this caused accuracy, clamping and noise issues.
I purchased a 8 inch / 200 mm 3 jaw chuck at a very reasonable price, A plate was purchased 15 mm thick and 210 mm diameter, to act as a backing plate to interface from the chuck to the existing fitting. Machined the plate to size. Added three M8 chuck studs.
Conclusions
The chuck aligned reasonable accurately
Billets of 100 mm and diameter of 85 mm now fit inside the jaws, machining is improved and the noise and possible clamping issues have been eliminated. If I reverse the jaws I can clamp a large 200 mm circular plate.
A heavy chuck has the advantage of smoothing out any backlash compared with a smaller chuck.
Not sure if the bearings will wear prematurely as it weighs 12 Kilo grams, however the stress from a protruding billet is considerable. I’m willing to fit new upgraded bearings if this occurs.