On Thu, Sep 10, 2009 at 10:20:07AM +0100, Andy Pugh wrote: > "F" controls the speed of travel in the direction of tool movement, > whereas "K" sets the speed explicitly in the Z direction.
In EMC2, K specifies the motion distance per rev in any direction. So if you're turning a tapered thread you just specify the feed per rev along the hypotenuse. If it is a 5 degree taper and you want 10 threads per inch, K would be 10/cos 5. > "F" could have been used for the lead in G33, but it would have been > inconsistent with its meaning elsewhere (though this is not > immediately obvious for conventional parallel threading operations) We considered "F" but chose "K" because we didn't want G33 to mess up the feed of non-threading moves. I can see it either way and I think the distinction makes no practical difference. > Incidentally, EMC appears not to be unique in this usage: > http://pdf.directindustry.com/pdf/delectron/g-code-programming-manual/14577-33189-_23.html Interesting - this one looks like it matches our usage exactly. > http://www.omni-turn.com/Media/Manual/G33%20threading.PDF but this is a lot more complex. > http://books.google.co.uk/books?id=i1cKWU9FBm4C&pg=PA84&lpg=PA84&dq=G33+threading+K&source=bl&ots=IlQv9IVzW2&sig=9qXwnEUHJ7aiFZhWdEDo1gmcR3o&hl=en&ei=ocOoStjbJOCfjAfC94XYBw&sa=X&oi=book_result&ct=result&resnum=2#v=onepage&q=G33%20threading%20K&f=false > Might make some sense, this describes the use of I, J, K for explicit > pitches in each cartesian direction, _or_ the use of F in the feed > direction. My problem with specifying endpoint (and implicit startpoint, which we always have) and pitches in various directions is the motion is overspecified. The vector end minus start gives a direction of motion. The slope K/I gives another direction. I guess you'd need to require the gcode programmer make them match, but I can't see why this extra work is a benefit to anybody. > If you wanted to turn a new scroll for your 3-jaw chuck you would need > the option of an "I" pitch, or to support "F" in G33. Not true. Even today you can use K in any direction. http://www.linuxcnc.org/docs/devel/html/gcode_main.html#sec:G33,-G33.1:-Spindle-Synchronized Chris ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
