Re: [CAD_CAM_EDM_DRO] Re: Has anyone made their own servos from DC Motors?

True servo motors have all sorts of internal differences to reduce
torque and speed ripple. I have some servos and you cannot feel any
cogging when you turn them by hand. They will run smoothly with a supply
of less than 1 volt. They also have very low inertia. Even though the
bearings are very free running the motors stop quite quickly if you spin
them by hand.

Having said that I am very happy with the treadmill motors on my mill.
If you fit a large pulley on the motors and run them slowly you can see
the speed varying slightly as the drive tries to compensate for the
speed and torque ripple. However in use I can't say I have noticed any
effect on the cut quality or accuracy. I could probably get higher
acceleration if I used proper servos but I have no real need to save an
extra 0.5 second per job :-)

Les

Blue wrote:

>Hi,
>
>I suggested this idea some 5 or 6 years ago and the reception from the list
>was muted. May be that was because I was going to use Philips washing
>machine motors. After all these things are 240 volts DC and very powerful.
>Any way I never got around to sorting one out because other things came up
>but I may give it a try and use one as a power feed until I get the rest of
>the system up and running.
>
>As far as I can tell the only difference, besides not having encoders,
>between a standard permanent magnet DC motor and one designed for servos is
>the weight, and therefore the inertia, of the computator. Quite how much
>this will effect the working of a motor used in this way is something I
>don't know. I'll have to put my money where my mouth is and give it a try,
>the trouble is I don't have a yard stick to measure it against.
>
>Regards,
>
>Terry
>
>
>
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