Dimensions for 944 hub machining

[wrljet]

Originally Posted by Chris Percival

The bearing inserts where made on the lathe, then pressed in complete. The bearing spacer is separate as it had to be made from aluminium so it doesn't rust..

Chris,

How do you get repeatable centering with that fixture held in a 3-jaw chuck?
(or is accuracy beyond the 3-jaw not an issue for the machining required on the hubs?)

Bill

[Chris Percival]

Hi Bill, not sure why you'd need repeatable centering, please elaborate?

[wrljet]

Originally Posted by Chris Percival

Hi Bill, not sure why you'd need repeatable centering, please elaborate?

A normal 3-jaw chuck only centers a part to within a few thousandths.
(of course some are better and some do have adjustable centering)

Say you check a bar and turn it round. Remove it and put it back into the chuck. Chances are good if you put a dial indicator on it, it's not centered anymore.

It looks like the same situation exists with the hub holding fixture in your pictures. Once that fixture is removed from the chuck, it'll be hard to get it back in again centered precisely the same way.

Thus, not repeatable.

Bill

[Chris Percival]

Ah I see, for machining both ends of the hub. I don't think it was ever a major issue, he just had to centre it as best he could every time he fixed it to the mounting tool and chuck. Resulting run-out of it all assembled was 0.01mm, so I guess he did a good job of that..