Re: [CAD_CAM_EDM_DRO] USB and ncPOD system

Tony Jeffree wrote:

> At 09:01 24/05/2007, you wrote:
>> The ability to download gCode DIRECTLY
>> to ncPod and run it from there may well provide a solution to the lathe
>> problem since it would not require a return path to the host computer.
>
> That would only provide a solution if the ncPod firmware is able to
> handle inputs from the encoder and modify its step rates accordingly.
> If that was possible it would significantly increase the appeal of
> the 'pod - right now I am looking for a solution to the lathe problem
> for my ongoing of Myford conversion.

Since this relates to ELS and a few other areas as well, I'll ask the questions :)
The problem we are trying to solve is locking the movement of the tools to the
rotation of the spindle?
The ideal solution would be a spindle that has a positional drive, with a big
stepper or servo, but since that is not going to happen, we need an encoder on
the spindle that gives the position information.

There seems to have been agreement that a single pulse is all that is needed
so you know when the spindle has done one rotation, but in that case the tool
may need to accelerate or decelerate if the spindle speed has changed?

Multiple pluses from the spindle along with an index pulse could be more
useful, as long as the firmware knows what to do with it? My own thinking has
been that a high speed, high res encoder on the spindle would generate a
reference pulse train, and the drive to the tool paths would basically divide
that down and so keep everything locked so that you could turn the spindle by
hand and the tool would move - back and forth in sync? An electronic version
of the gearbox on the lathe, except you can change the gear ratio depending on
how far you are along the job.

Am I missing something?

--
Lester Caine - G8HFL
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