Re: Threading on a lathe with EMC

Chris, et al:

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.

Just a thought.

Hugh Currin
Klamath Falls, OR

On 29 Oct, ccs@... wrote:
>
>> Is the problem that the hobby machines do not have a proper spindle encoder?
>
> No, as hobbyists we should all be capable of fitting one. The problem
> is that the architecture of EMC will need some adaptation to be able
> to coordinate other axis moves to an encoder on a spindle that cannot
> be servoed in position. So your choices are servo the spindle with a
> positioning-class drive or modify the innermost workings of EMC.
>
> To some extent, the problem may be that those doing development don't
> have lathes with spindle encoders. Most of the development work has
> been mill-oriented.
>
>> Has anyone done a feed per revolution for EMC?
>
> Not of the sort that is needed for threading on a lathe. There exist
> CNC codes to turn such a mode on and off, but there is no program code
> to slave an axis to the spindle revolution.
>
> Chris