Re: More CAF...

Fred Proctor wrote:

> From: Fred Proctor <proctor@...>
>
> Arne Chr. Jorgensen wrote:
>
> >
> And there is other stuff. Do you really click those menu buttons on
> the EMC panel out in a workshop. I convinced a manufactor to put in
> an encoder hand wheel for moving the axis once. The reason was that
> I found it so difficult to jog the axis with switches, and I would
> like a feed rate over ride as a knob. Maybe an analog joystick for
> the axis ?
> <
>
> I've been asked many times to support using a handwheel encoder, which
> could be put on the unused 4th axis encoder input if you have a 4-axis
> STG board and a typical 3-axis mill.
>
> My thoughts on this would be to selectively slave one of the three axes
> to the 4th axis encoder, so that the 4th axis encoder would serve as the
> input to the PID on the slaved axis. Then, as you moved the handwheel,
> the slaved axis would follow it. Varying the scaling on the 4th axis
> encoder input would allow for varying sensitivity. It gets tricky since
> you have to make sure the slaved axis doesn't jump when it gets slaved
> and de-slaved. Has anyone done anything like this?

It really doesn't sound too tough. What you have to do when you enter
the MPG (manual pulse generator) mode is to read an initial position of
the MPG channel, and then use a difference from that saved 'reference'
value for all moves. Or, to make it the same every time through, is to
make the controlled axis move by the difference between the last pos
and the current pos of the MPG channel.

> I have used a $9.99 PC joystick to move the EMC around. The stick
> controls the XY motion and the buttons control Z. Would anyone want
> this? I would put it in the xemc, which could sense the presence of a
> joystick and default to normal behavior if none were present.

Well, this probably would work, but the STG card has those A/D
converters on it. It might be a lot better to allow them to be used,
as they are likely to be a lot more stable, and also could be used to
input a 'jog' command from some external device, like a touch probe
or EDM current. I (and I think a few others) have interest in making
very simple sinker EDM setups, where the EDM current controls
the rate of feed on the Z axis. One would expect you'd want to run a
different version of xemc for this hack (although maybe it could be
arranged by a parameter in the .ini file.)

Jon