Re: [CAD_CAM_EDM_DRO] Re: Belt vs. Direct Drive

At 08:17 AM 1/3/03 -0000, you wrote:

>With direct drive, unless you are very confident of the alignment of
>motor spindle with the screw, you should always use a coupling that
>is tolerant of misalignment;

Not at all ... I hung motors directly on screws once using rigid couplings,
which I made in one op for good concentricity. The motors just overhung the
screw ends, right out in space. The motors were drag-linked to the machine
frame using a stay from flange to the anchor point. The stay can be
slightly flexie from side to side as long as it doesn't stretch or shrink
when torque is applied. This is the most rigid arrangement possible for
transmitting torque, and the motor and screw bearings have no trouble
supporting the motor weight. Try it, it's clean, simple, quick and very
effective.

Regards, Hoyt McKagen

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