Re: [CAD_CAM_EDM_DRO] Re: Re: EMC Lathe mode.

Art Fenerty wrote:

> >
> > I really don't like this idea... what happens if the computer gets set
> > with what it thinks the spindle speed is based on the speed when
> > cutting air, and then gets really suprised at what happens when the
> > tool touches the work?
> >
> Why, does the spindle slow down to any signifigant degree?? This is
> beginning to sound like lathe CNC really require a VERY tight control of
> stepper motor speed versus Spindle speed. Wouldn't any PC have a latency in
> reading the encoder, and making decisions about wether to pulse the motor
> yet? What kind of latency would be considered too much?

No, the latency will be very small! That's the whole idea!

If you use an encoder that gives, say, between 500 and 2000 counts
per rev., then the computer can make a position and velocity adjustment
EVERY time it reads the encoder counter! If that is 1000 times a second,
then there are 1000 course corrections every second. Even if the
spindle is slowing down significantly, the thread will still be PERFECT!
In fact, even if the spindle totally stalls, the thread, up to the point it
stopped, will be correct. At some point, a software limit could detect
that the spindle was, say, 20% below requested speed, and declare a fault,
also causing the tool to retract in X to the clearance radius.

Jon