Workholding on the lathe

[Wongster]

Hi folks,

I'm planning right now to make an ER32 collet chuck that is to be bolted onto the spindle flange of the Proxxon PD400 lathe. The spindle flange is 100mm in diameter, has PCD of 83mm for the M6 mounting screws, and recess of 70mm in diameter. The mounting holes are threaded M6. The chucks are held on the flange by either 3 or 4 M6 screws (3 for 3 jaw chuck and 4 for 4 jaw) inserted from the front of the chucks.

I bought a pieces of mild steel round stock of slightly bigger than 100mm and of 42mm thick. Both sides were cut in a bandsaw and so are rather rough. There is also a layer of "skin" on the cylindrical face. Here is the piece:



I am wondering how I can hold it in the lathe to start squaring up the 2 faces and the side.

Here my thought after having a "chat" with andyf:
1) Drill 3 clearance hole for the M6 screws (PCD 83mm) with deep counterbores. Andy suggested drilling the holes and counterbores slightly bigger to allow wiggling room for the register recess to seat properly. The holes will be done on my little Sherline mill on a rotary table (if I've enough head room. Otherwise, wait for 8 weeks for the arrival of the Wabeco F1200).

2) Faced the other side and turn it down to fit into the 4 jaw chuck (my 4-jaw opens up to max of 100mm per the thin manual it came with, chuck jaws reversed).

3) Indicate in the turned portion in the 4 jaw chuck to turn off the rough surfaces and machine the register recess.

4) Flip the work around and bolt in on the spindle flange directly.

5) Reduce the diamter of a section of the workpiece for the nose. I should be very close to the head of the M6 capscrew.

6) Thread the nose for the ER32 Nut (M40 x 1.5) and bore the taper (this will be my biggest challenge).

7) Dance in joy before starting to test for run-out - to at least be happy for a moment that a job has been completed.

Would that be how you folks do this? Any other ways or improvements to make it simpler?

Regards,
Wong