Page 43 explains what Jon was saying about the index only used once when tracking is started. http://www.linuxcnc.org/docs/2.2/HAL_User_Manual.pdf
Tracking enables the index and then once it occurs the counter (in software I imagine) is cleared, as well as the flag which now results in the index being ignored again. For tapping (or lathe threading) at this point the speed is monitored to ensure the moving axis follows the inclined plane that is the thread. Again as an example: If you are tapping 20 TPI then each turn of the spindle is 0.050" and a 90 line encoder creating 360 edges means each edge is a distance of 0.050"/360 or 0.000138889". Even an 4 TPI thread which is getting pretty coarse now is 0.00069444" inches so again a Z axis with 0.0005" resolution shouldn't have any trouble with that thread if it's a single point tool. What it would do with a tap I don't know. So theoretically you can hard code step pulses to spindle pulses (used as distance to handle rounding). And turning the spindle by hand if the reaction to the spindle is fast enough the tap wouldn't break or slip in the holder. But I suspect one probably wants better than Z axis resolution on the spindle so the changes don't affect the Z until several encoder pulses have occurred. I haven't found the source code that does this yet. Not sure what to look for. This site http://www.linuxcnc.org/docs/html/drivers/hostmot2.html#sec:hm2-encoder for example just repeats the HAL user manual and expands a bit on MESA configuration. John > > > You don't want to clear the counter if it can be avoided, for example the > index > logic does not clear the counter, but rather latches the count at index. The > driver presents a number (position) that is cleared on index, but the hardware > counter is not cleared. _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
