Re: [CAD_CAM_EDM_DRO] Rigid Tapping--How is this accomplished?

jmorrphd2 wrote:

>Dear Fellow Group Members:
> I would like to know how rigid tapping is implemented. I know
>that the Z-axis feed and the rpm are synchronized such that the
>Z-axis feed (in distance per minute) is equal to motor rpm x thread
>pitch. How does the drive motor "measure" its angular displacement
>or speed?
>

With a spindle encoder. These machines have an encoder attached to
the spindle to precisely sense shaft position.

> Is the Z-axis speed adjusted continuously as a function
>of motor speed variation?
>

Yes, every servo cycle, the spindle position is measured, and a new
Z velocity is calculated to keep the Z feed and spindle in sync. When the
spindle reverses to back the tap out, the Z axis slows down and then
reverses in sync.

Jon