Re: [CAD_CAM_EDM_DRO] USB and ncPOD system

Lester Caine wrote:

>
> So currently if you 'rocked' the chuck back and forth you would loose
> position?

No, it won't lose position, but it will gouge on the back side
of the cutting tool. The Z feed will stay motionless until you
return the spindle to the point where you began the reverse
movement, then the feed will pick up.
I can't see that there should be any problem running the
spindle in

> reverse - in fact the discussion was when using an 'electronic gearbox' you
> would switch the spindle to reverse after withdrawing the tool in order to
> move back to the start point and maintain accurate sync.
>

I don't understand the reason EMC2 stops feeding when the
spindle reverses. It would not be normal for this to actually
happen, but obviously there is some decision logic that depends
on the spindle moving the "right" way. Maybe it has something
to do with the initial synchronizing at the beginning of the
spindle sync'ed movement.

>
>>Of course, this can't be done with just an index pulse, as you pointed out.
>
>
> But the index pulse IS essential if you move the tool back without reversing
> the spindle as you need it to re-establish synchronisation again when
> re-starting the cut.
>

Pulling the tool out, backing up rapidly and then re-synching is
a much faster and more flexible way to do it. And, since there
is no gearing to re-synch, you can cut any thread, imperial,
metric or irrational that way.

Jon