# VFD for lathe, sensorless vector



## hacklordsniper (Feb 7, 2015)

As im upgrading my lathe with VFD and larger motor, i have 2 options in sensorless vector control. It is speed control or torque control, which one is better for lathe and why?


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## Wizard69 (Feb 7, 2015)

hacklordsniper said:


> As im upgrading my lathe with VFD and larger motor, i have 2 options in sensorless vector control. It is speed control or torque control, which one is better for lathe and why?




I would have to say speed control.   The only drive technology I have any experience with torque control is for large extruders in the plastics industry.  I would think that running at a fixed speed is more important than a fixed torque.  

However this thought did come to mind, would torque control compensate for diameter variance in facing operations?   I don't really believe it could be reliable that way.  Some drives can switch dynamically between the two methods and some after a reconfiguration.  If the drive is capable of this then you certainly could do some testing, in the end I think speed control would be easier to work with.


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## adrianjs (Feb 23, 2015)

You definitely need speed control. If you try torque control then you will end up breaking things and also getting an aweful surface finish.


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