Probing with EMC
For the purpose of this documentation, probing shall be defined as a process of measuring items on on the table of a CNC machine equiped with a "probe switch" installed in the machine's tool holder. Under programed control, the machine “probes” the surface of an object by moving the probe switch towards the surface of the object until the the probe switch registers contact. At this point the machine immeadiately stops motion and the coordinates at the point of contact are recorded.
As a single operation this procedure may be used to check for flatness across a surface, measures clearances, etc... However, if this this proccess is repeated across many points of a model is it then possible to digitize the surface of the object.
Emcprobe is a program that works in conjuction with NIST's EMC controller (www.linuxcnc.org) to automate the probing task so as to allow digitization of 3-D models. Emcprobe is a console application that talks directly to EMC through the software message passing mechanism built in to EMC, called NML
Once executed, Emcprobe reads an initialization file created by the user and then begins the probing proccess. During the proccess, emcprobe works through the regions defined in the initialization file, and outputs a g-code file that may be used in reproducing the part. Coordinate data is easily extractable from this resulting g-code for use in other programs.