Re: [CAD_CAM_EDM_DRO] 3d digitizing

Andrew Werby wrote:

> The question I have is that can EMC be set
> up for digitizing? I have already installed EMC on my Linux PC and
> been messing with it a little. If it cannot do digitizing, is there
> another reasonable software package available for doing this?

EMC as it stands can't do this. But, EMC is now using a user interface
programmed in Tk/Tcl, a simple scripting language that is quite powerful

and reasonably fast. Since it is controlling the rest of EMC at a high
level, it could be used to digitize. You need some way of getting info
from the probe into the computer. Possibly a simple contact probe could

use an unused parallel port bit. A probe that sends distance info
through
the serial port could also be used.

The mechanism I imagine would be the user enters the XY coordinates
of a region in the XY plane, and a safe height for the probe to clear
the
tallest point in the region. The probe would be raised to the clearance

plane, moved to the lower left coordinate of the XY region, and the
probe lowered until contact is made. For fine resolution, the probe
could
be slowly retracted until there is no contact, then lowered very slowly
until contact is seen again. Then, the probe is raised, the XY location

steps to the next point to read, and the cycle repeats.

This wouldn't be fast, but could be left to run overnight.

With a probe that gives a distance reading, you would just have to
keep the probe within its active range, and the height would be the
Z (spindle) position - probe length.

The X and Y axis moves could be sent to the EMC system as if they
were entered as MDI commands, and the Z axis feeling for contact
could be sent as if manual jog buttons were being pressed. The TCL
script could write the results in an ASCII file with X Y and Z
values.

Jon