Re: [CAD_CAM_EDM_DRO] Best source for Servo's ??

turbulatordude wrote:

>Hi all,
>
>Seems like there are bunches of source for steppers but no one talks
>about surplus sources for servos.
>
>Are there any guidelines to look for in possible candadates for servo
>motors ?
>
>

First, the motor needs to be reversible, and either permanent magnet field
or shunt field. (Series field are always unidirectional without much
messing
around inside.)

Second, you want one with minimal cogging, both magnetic and in the
velocity and
torque of the motor. The first problem, magnetic cogging, can be felt
in some
motors just by turning the shaft by hand. Motors with more commutator
segments
may be better on the latter, but it is not a guarantee.

In most cases, for CNC motion applications, motors designed to produce heavy
torque at lower speeds work better, especially for milling machines.
You don't need such
high belt reduction ratios with these.

A motor fitted with an encoder makes for a simpler installation.

Ball bearings are really a GOOD idea. Many cheap motors will have
sintered bronze
bearings, which do fine on continuous rotation, but tend to wear rapidly
in the low-speed
stop-and-start mode of a CNC motor.

Jon