Re: [CAD_CAM_EDM_DRO] Re: Threading on a lathe with EMC

> Is should be possible to fit a Variable Frequency Drive to the lathe
> spindle. Then one could control the torque using a voltage output from
> the computer. This is then very similar to a servo loop. If one fitted
> an encoder and tach to the spindle these would feed postition and speed
> back to the computer which would adjust torque to complete the loop.
> Could this be used with appropriate control loop variables in EMC to
> deal with the spindle as simply a rotary axis? It would be very slow
> reacting but the variables in EMC for servo loops might be able to deal
> with it.

EMC expects every axis to position perfectly, so any error caused by a
spindle servo loop which is 'slow reacting' will show up in the part.
There are certainly spindle drives that can keep position accurately,
but it is far above the normal requirement of simply keeping a steady
speed. This is why there has been some talk in small machine circles
of simply using a hefty servo for a spindle motor. Make it powerfull
enough and you have indexing capability, too.

Chris