hi Jonathan.

Originally Posted by george ukTwinning an X, Accurate Z position over large time running jobs



If those are causing a problem, then it should be solved by setting up the system properly.
understood, i have been reading up on what experiences people are haveing using twin X, and i notice that a few were having problems homing them both, i just thought that these may be an easy way round that, but, yes defiantly, if people are lossing steps on X, its machine problems or bad design .

Z Axis, for what i want to do, thats more important, some of the jobs we are looking at have run times going over 5 hours plus, ( am doing 2 machines ), so it seems to be a reliable way of making sure any lost steps in Z dont compound themselves, as they would be corrected immediately.

You can only gain anything below this speed, since whether the position is inferred from an encoder, or the back-emf, doesn't change the rest of the algorithm. That's the reason why the stall detect feature, e.g. on the AM882 driver, only works above 300rpm - it can't sense the position below that speed.
Thankyou for this, i like information put this way, short sweet and direct,