Matt Shaver wrote: > > > Here's what I think Jon is talking about: When in a rigid tapping > cycle, the Z axis is "slaved" to the rotational position of the > spindle. The spindle will have its own characteristics of motion, but > we don't always have tight servo control over them. For example, at the > bottom of a tapped hole, the spindle must reverse, but it may come to a > stop with a jerk due to high friction (you've probably experienced a > tapping operation where the tap wants to move in small jerks rather > than smoothly cutting). At this point the Z axis should probably be > controlled with no limit on jerk (and maybe no acceleration limit > either) so as to maintain the spindle-to-Z-axis position relationship > which is critical since they are now _mechanically_ interlocked through > the tap and it's threads in the workpiece. > > Yes, that was my concern. Although the tap may jerk a bit, the torsional flex in the tap and mass of the spindle assembly will already somewhat damp these sharp movements, making what the Z has to follow a bit less drastic. But, you certainly want the Z to follow the spindle encoder as closely as possible, introducing the minimum amount of smoothing and delay as you possibly can.
Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
