Re: [CAD_CAM_EDM_DRO] Re: Custom made bearing for lathes

On Sat, 02 Feb 2008 07:01:02 -0000, you wrote:

>my lathe is converted to CNC and I will attach linear encoders with 1
>micron steps. I presume this is fairly precise ( although I know at 1
>micron there are vibrations, causing the encoder to signal them ). My
>lathe has less then 9 micron shaft run-out. Do you think is enough?
>At the "air spindle lathe" I want to be able to turn objects of about
>5-6 centimeters (2 inch + ) in diameter.
>I would need some plans or a solution somebody tried and worked, if
>possible.
>If this proves too hard. what about an oil bearing? What is the
>typical run out / stiffness of it? Are they easier to build than the
>air bearings?

What's the problem with ordinary bearings?

Abec9 or Class A bearing usually have a run out of less than 3 microns,
it's about the best your going to get off the shelf, and probably more
than accurate enough for you.

A micron is a thousandth of a millimetre. Unless you temperature control
your lathe it will likely expand and contract more than your minimum
resolution.

For example - suppose your lathe bed is Cast iron, it will
expand/contract .0102 microns per millimetre per degree C.

Steve Blackmore
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