On 24 January 2012 21:09, Kent A. Reed <knbr...@erols.com> wrote: > At best I'm a dilettante with machine tools and certainly I'm no expert > with a lathe. That not withstanding, long, long ago, I was taught to cut > a tapered thread on a manual lathe by shifting the tailstock over. It > seems to me this would necessarily mean the thread pitch was measured > "along the hypotenuse" since the line of motion of the saddle is > parallel to that hypotenuse.
This would be the case if the tailstock is set over, however many lathes had taper-turning attachments which basically slaved the cross-feed to the longitudinal using a bar. In that case the taper would be along the adjacent line. I wonder if anyone ever noticed that these had different effects? Both NPT and BSPT have the same taper of 1/16 (3/4" on diameter per foot of length). This yields a correction factor of 1.000488, which could be applied as a constant in the G-code or, considering the munged-togetherness of taper threads, and the fact that it is half a thou in a 1" run, ignored. It would be more critical for higher angle taper threads. -- atp The idea that there is no such thing as objective truth is, quite simply, wrong. ------------------------------------------------------------------------------ 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
