Re: Re: EMC Lathe mode.

On 2 Oct, CAD_CAM_EDM_DRO@yahoogroups.com wrote:

> No, completely wrong, assuming you are hooked to an encoder counter.
> In between pulses, you have no idea what part of the revolution you are
> in. The only way this would work is if the computer's interrupt was
> synchronized to the spindle pulse. But, one interrupt per revolution would
> be totally inadequate. You would need to have a synthesizer that produces
> a roughly constant number of interrupts per second, but would reference
> every N ticks to the spindle pulse. Sounds like a nightmare!
>
> If you use a spindle encoder and encoder counter, then you have no
> idea where the spindle is, you only know that it is somewhere in the
> Nth revolution. You can't sync the Z axis to that. You need much finer
> feedback.

I THINK that if you only have a single pulse per revolution, it could
still be workable.

The computer could determine RPM from the single count within a few
rotations. ( A well written program would wait for a relatively stable
speed and announce an error if there was too much "wobble". )

From RPM and a single pulse, the CPU could then calculate where the
spindle is in its rotation.

Frankly, I don't like the idea, but with enough flywheel inertia and a
small enough cut, this could work just fine.

In fact, I think there IS such a machine produced commercially, if my
poor sad memory can be relied upon ...

Alan

--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta