Ok, calling on the collective knowledge of machinists...
I can obtain a blank backplate for a lathe chuck. It requires the centre drilling and tapping M40*4 for the lathe spindle and shoulder machining to take a chuck...
What is the correct procedure for drilling/tapping/machining?
Do I drill out the centre first, then machine the shoulder with the backplate attached to the spindle?
How is the backplate initially held when performing the operations required to make it fit?
How would you do it?
Your advice muchly appreciated