Clausing 6913 Lathe ==> Machining A Chuck

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This page details how I machined a chuck to fit my lathe. I bought a cheap imported chuck from Jeff Beck, who sells cheap machine tool accessories. Jeff is a fantastic guy from whom I bought things in the past. He is very customer oriented and always makes things right.

Anyway, what I bought from him was a L00 Four Jaw Lathe Chuck.

It had to be machined to fit the chuck to the backplate. This is actually a good thing, because machining them on the customer's lathe can greatly increase accuracy of the chuck. Machining a chuck can correct problems such as sligntly bent spindle or mars on the spindle mating surface, for example.

I did, essentially, three things:

• Machined the face. The point of this is to make sure that the face surface is percisely located in the plane perpendicular to the axis of rotation.
• Turned down the mating plug. The point of this is to make sure that the chuck slips over it and yet is firmly centered. Here you want to be super careful and get tight fit, especially for three jaw chucks.
• Aligned the chuck body to point straight along the axis of rotation. The issue is that the chuck's body is not perfectly machines and it does not point straight, even though it is held tightly against a perfectly perpendicular surface. The correction I did was to insert paper shims between the chuck and the plate. Before the shims, runout of a straight rod 10" out of the chuck, was about 0.040". After the shims, I managed to get it down to 0.004" (0.002" from zero).