On 5 May 2010 19:00, Leonardo Marsaglia <leonardomarsagli...@gmail.com> wrote: > > So andy, you think that with G33 i will have the wait for the index pulse as > if i'm doing a regular thread along the Z axis? and because of that it > wouldn't be quite right for making lobes..because the movement won't be > continuous Correct me if i didn't understand
It is worse than that, really, as it will only do straight, linear moves which always start at the index pulse. A cam is made of at least 2 arcs (and probably more) starting at different times during the revolution. I think that a HAL module to offset X by an amount dependent on the current spindle angle is the most likely solution. There is a utility called "comp" that makes this rather easier. http://linuxcnc.org/docs/html/hal_comp.html You would wire the X-axis-position-command into the new function, and then thoe output would be a synchronously-offset X-command to feed to the PID or stepgen function. The function would need a reverse-path to take the actual position, subtract the offset, and pass that back to the axis-feedback pin so that following errors would still be detected. One reason I like this approach is that it means that you don't need any special postprocessor, you can use simple G-code and let the HAL module read the cam profile out of a file. (This also means that you can change profile very easily) You would probably still use G33, but only to define the amount of extra cut per rev to apply on top of the profile generator. Depending on how fast your X-axis is, this would also work with a conventional lathe tool rather than a milling cutter. It wouldn't be as fast though. -- atp ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
