On Wed, Oct 21, 2009 at 02:37:47AM +0200, Haberler Michael wrote: > > I'm a CNC retard, so here's my question: where is the benefit in > incrementally controlling the feed depending on continuous spindle > position updates as opposed to just assuming the spindle angular speed > stays constant for the next full revolution?
Because that assumption is often wrong and you get bad threads, especially on low power spindles or difficult to cut material. > it's a pity - I own a mill which sort of was designed as a Mach3 > peripheral and it does rigid tapping fine with a 1 PPR optical reflex > encoder on the spindle with Mach3 No, you are mistaken somehow and I bet it's a problem with terminology. Without full spindle feedback OR precise positional control of the spindle, it is impossible to rigid tap. Rigid tapping is running a tap that is firmly (rigidly) attached to the spindle. Here is Kirk W's video of his machine rigid tapping a 4-40 thread. You can see at 1:36 that the tap is rigidly attached to the tool carousel. http://www.youtube.com/watch?v=HtMHUPHUVkw If you are tapping with a free running spindle and 1ppr feedback on mach3, you must be using a reversing tapping head or a floating holder. This is not rigid tapping. There is no reason why you can't use your tapping head with EMC2. You would not need spindle feedback at all. I have tapped many holes with a Tapmatic on an old CNC mill with a varispeed spindle and no feedback whatsoever. It is a minor pain to set up but once it's going, it works OK. ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
