CNC is one of those acronyms that we are stuck with. The more things chance the more they stay the same.
The term "Horseless Carriage' has mostly died out except here in Colorado where they still issue legacy "Horseless Carriage" license plates for extremely old vehicles. But today they still call the 4 wheelers a CAR (riage) and Auto-mobile. Note that in G-Code we still use M2 to indicate the end of a program and many machines still use M30 which was the original M-Code to start the rewind of the NC paper tape back to the leader section. The % sign was used to indicate the end of the feed leader and beginning of the actual program. At the tail end the % told the teltype to punch the trailing leader (3' to 7' different machine readers had different needs). A good way to describe the differences between CNC and NC would be that you could not edit an NC program. If there were changes you could load a tape, line by line, via teletype with tape reader, add or remove commands by typing them in as a new tape was made. Another legacy factor that still haunts us is that NC code did not support cutter compensation and was all spindle center. Most CAD/CAM systems still program this way only using G41/G42 for very minor wear corrections. ( hang the lazy b@$tards ) An NC tape reading control - that would read a single line of code and execute it, then advance the tape reading the next line and execute etc. BTW this is also where the history of the term Single block came from, not allowing the tape reader to read the next line until you pressed the start button. A 2 axis control unit was the size of a US family home refrigerator, or 1m x 1m x 2m for those elsewhere in the world. I still have a few coffee cans full of the Aluminum 35mm film cans with many of the punched tapes I had to make in College to earn the title of CNC Machinist and programmer. Anyone remember Florida and the issue of "Dangling shards". That is the horror story of paper tape. Once you made a good part. Cut and passed QC inspection you ran the paper tape back through and punched good quality mylar tape that was dependable. Now, slowly we might see CNC fade out. I see 3D printer and pick and place machines that have just a 2 line display and loads program via USB or SDHC card and just runs, no provisions for editing at the machine itself. In the very high end manufacturing machines I could see a single control terminal running an entire flexible machining cell, or even multiple cells. Likely it would use a tablet device as a slave to allow remote access when setting up a specific machine. Automation doesn't really put too many people out of work, it just shifts job titles and responsibilities. Switching over to robots to load and unload machines caused a huge improvement in quality since the part to part time interval was consistent, as well as less dropped parts and a cleaner work environment for operators. It provided time for operators to do actual measurements vs depending on simple go/nogo gages. Greg, Out yonder in Colorado ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
