Re: [CAD_CAM_EDM_DRO] USB and ncPOD system

Steve Blackmore wrote:

>>> Am I missing something?
>> Nope, what you need is a rotary encoder with an index
>> pulse. Generally something in the 200-254 PPR range is sufficient
>> with 254 PPR for a metric thread on an English machine.
>
> ? A single pulse is totally adequate if implemented properly, Conect
> lathes and BBC B computers running basic were doing it back in the
> seventies and Mach still does it now. I must have done thousands of
> perfect threads using 1 ppr.
>
> The pod/mach combination simply can't read that pulse quickly enough.

What CAN'T be done with a single pulse?
It is reliant on a stable 'phase lock' with the pulse generator that is
driving the linear feed, which is what fails if the speed is not stable -
which is why it's 'adequate'.
I suppose I'm coming from the end off things because the alternative is the
fourth axis on the mill and machine cutting treads, so I am used to knowing
the fourth axis position.

The next problem I've got to look at is clock fusee for a show in July, which
could either be turned with a variable pitch, or milled on the 4th axis.

--
Lester Caine - G8HFL
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