Question Re: Work Offsets

Hi Tom

IIRC you need a G91 in your G-code file. If you have homed your
machine manually by jogging, use G91 as the first line. That should
fix it. Unfortunately I do not have my EMC manual in front of me,
just check the exact syntax.

Stephan
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "inetd_conf" <benedict@h...>
wrote:

> I had some odd behavior on an EMC system running BDI 2.16:
>
> I spent the last two days PID tuning to get the axes running
> cleanly. They're running cleanly now, and in the process I had

the

> opportunity to set up and run a number of toolpaths, mostly
> prototyping in pine so a tool crash wouldn't be disastrous.
>
> Today I tried to run an actual part. I used an edge finder to
> indicate in the workpiece, and set my zeros by right-clicking on
> each axis in turn and setting it to zero.
>
> When I ran my program, it proceeded to crash the tool into the
> workpiece (even though the first move is to go to (0,0,0) and

raise

> the quill to 2.0" off the top of the workpiece.)
>
> I carefully checked my zeros and loaded a new part. Same

behavior,

> only this time it snapped the end mill off.
>
> Before changing a tool and crashing it again, I played around with
> it.
>
> In MDI mode, if I typed "G0X0Y0Z0", it would go to (0,0,0) in the
> relative coordinate frame. If I ran the program, it would attempt
> to go to (0,0,0) in the absolute machine coordinate frame (the Z
> value of which was well inside the workpiece).
>
> I stripped the entire header off the program file so it starts

with

> that "G0 X0.000 Y0.000 Z0.000" statement. Same behavior.
>
> What am I missing here? I thought MDI and running a program was
> essentially the same thing. I didn't know one would run in one
> coordinate frame and one would run in the other. I'm REALLY

puzzled

> why this behavior didn't show up during the two days of PID tuning

I

> did.
>
> I could seriously use the help. I'm dead in the water, and not
> really interested in busting any more tools or driving any cutters
> into my vise or mill.
>
> Tom