On Tue, Jan 24, 2012, at 10:02 PM, andy pugh wrote: > On 24 January 2012 21:52, John Prentice <j...@castlewd.freeserve.co.uk> > wrote: > > > (b) For most practical tapered pipe threads no one will notice the pitch > > error. On one hand I think it is unusual CNC behaviour in threading (so > > possible difficulties for CAM users without a special postprocessor). But on > > the other hand the case of the angle not being small but being 90deg does > > appear to allow cutting of scrolls - has anyone ever tried this? > > Not yet, but I am very much considering making a 3-jaw chuck milling > vice thingy, so will need to then. >
And that is the reason EMC measures pitch along the hypotenuse. A fairly famous quote from Allan Kay goes: "Simple things should be simple, complex things should be possible." With the current configuration, simple things (straight threads) are simple. Complex things (tapered threads, including the extreme of a "flat thread" as in a three-jaw chuck) are possible. You have to do a little trig and make a minor correction if you want gage perfect pipe threads, but it is certainly possible. If EMC always calculated pitch along the Z axis, then the flat three-jaw-chuck style thread would be impossible. That is the reasoning behind our "stubborn insistence" that EMC work the way it does. We would rather have some complex things be a little more complex, if it lets us avoid making other complex things completely impossible. John Kasunich -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
