> On 31 August 2016 at 07:42, <dan...@austin.rr.com> wrote: >> Got into a bizarre argument... so of course it was initially "Computer >> Numeric Control". I was noting people breaking it down to explain it to >> people as "which means it's 'computer numeric controlled'" but that seems to >> add nothing to the meaning. In fact it's confusing. Before CNC, there was NC (or tape-NC). No computer. The Moog Hydra-point control read a wide tape which had the positions coded on it with air nozzles, similar to a player piano. The position encoders on the machine slides also used many holes and air nozzles to encode position. The control was entirely pneumatic. The comparison between commanded position and encoder position controlled Moog hydraulic servo valves to move the machine by hydraulic motor and leadscrew. That was an example of "extreme" NC.
GE made controls that were electronic and digital, and used traditional (but very limited and concise) G-code. These had hundreds of boards full of discrete Germanium transistors. It was all functional logic, no computer. The basic control did positioning only. If you wanted linear interpolation, you had to add a couple hundred more boards. if you wanted circular interpolation, add another couple hundred boards. There was no CRT, just an LED position display and paper tape. Bridgeport and others had early CNC systems that worked about the same way, no CRT, just an LCD display with very terse information. Finally, in the late 60's or early 70's CNC with CRT displays came out. So, the term "CNC" was used to distinguish the advanced capabilities of having a computer IN the machine control, as opposed to the limitations of the earlier NC systems. Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
