On 31 Aug 2016, at 07:42, <[email protected]> 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.
unless you know the history, which most "consumers" don't; and that makes it difficult to explain to the lay person. Ssome notes that might help: "Early industrial automation systems were mechanical, and were based on cams which moved parts of a machine in specific ways, and the cam-auto lathe was common in factories. The next step was Numerical Control (NC), in which servo motors controlled by electronics moved machine slides to positions specified by holes punched in paper tape. (That's where the N part comes from) Finally, as computer systems became more widely available, Computer Numerical Control (CNC) allowed more flexible control of slide movement by cutting the time required to create punched paper tape and, latterly, adding many user-friendly features to the process of programming and control. (You could say the word Computer was added on at that stage simply to distinguish between the existing Numerical controls using paper tape, and this new variation which added the flexibility associated with the computer). A lot of the early development work for NC and CNC systems was done by universities and military research and development teams, and there were early moves to standardize the way the systems worked, leading to the RS274 standard for commands to control these machines. This led on to the Next Generation Controller (NGC) project by the American National Institute for Standards and Technology (NIST) which resulted in a set of standards for the RS274/NGC control language interpreter and produced a core set of software for controlling the movements of the axes of a machine tool. That core software lies at the heart of much of the CNC control software currently in use industrially, as well as in the home workshop. Any specially written custom control systems should conform to the RS274/NGC standards so that all CNC systems should respond in a similar way to a set of standard commands. There is room, though, for systems to add facilities or to interpret unassigned commands in a specific way, and commercial systems inevitably differ in detail as manufacturers attempt to sell systems with added bells and whistles." That's a short extract from an introduction you can download free at: http://www.cncintheworkshop.com/Part_1.html by taking the link at the top right of the page where it says "Download the article here". The notes were written for entrants to CNC machining, so they would be more comfortable with all this than a lay person. > > It's computer-controlled, sure. I say "computer controlled" for people who > don't know the term "CNC". But what is the "numeric" adding? I presume that > meant something in like the 80's, but it's not used anymore. Computers use > numbers... and bits... and memory... and code... and electricity. It doesn't > seem to convey anything now but implies there's some special number thing > going on, which is why I always just say "CNC" or "computer controlled". > > Thing is, people occasionally become confused how a laser cutter or 3D > printer is NOT "computer numeric control", we never call those CNC. Well, > they ARE all computer-controlled, equally so, really. Yes. But the way they have been marketed avoids pointing that out. They are a "new" technology for lay persons who are keen on "new" technology and computers and stuff, and who often have no background at all in manufacturing technology and often would not appreciate the links between metal-cutting machines and plastic printing machines. They might understand that link better once they have played with their printer, of course. So in one sense they have no knowledge of the background history, and are comping at computer control a different way around. > And numbers are involved. But the term "CNC" seems limited to mills, > routers, and plasma. A waterjet or wire EDM, I just hear those without the > "CNC" in front, because there's no manual waterjets around. There are > handheld plasma cutters through. > And older oxy-acetyline burners mounted on a pantograph arm whose motion is controlled by a simple optical sensor following a line drawn on paper. These used to be common. and they involved minimal electronics and no computer at all. In fact they were quite crude, but also reasonably effective. Our local steel merchant used one for years, until very recently. > It seems like expanding it to "computer NUMERIC control" implies that > something entirely different in its core concept than laser cutters or 3D > printers... or, like, a paper printer, and people ask what that is. > > I was arguing the best answer is "CNC just means CNC, and specifically > cutters and plasma". Or just means it is computer-controlled. The N belongs to history, but we are stuck with it, unless you just say these are "computer-controlled" machines. Marcus > > > Danny > > ------------------------------------------------------------------------------ > _______________________________________________ > 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
