I thought that was "hanging chad" rather than "shard". See https://en.wikipedia.org/wiki/Chad_(paper)
> -----Original Message----- > From: Greg Bentzinger [mailto:[email protected]] > Sent: Wednesday, August 31, 2016 1:21 PM > To: [email protected] > Subject: Re: [Emc-users] What does "CNC" really mean? > > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
