Ian W. Wright wrote: > Hi, I have a question for you electronics experts out there...... I > have added a little lathe to my mini-mill which I want to act both as an > 'A' axis or an independent lathe. So, I would like to use the same > stepper to drive the spindle in both cases. As it stands at the moment I > have a driver board driving the 'A' axis as normal and a separate driver > board fed from a simple oscillator for step generation feeding it as a > lathe. Each driver ends in a plug so that I can unplug the lathe motor > from the 'A' axis driver and plug it into the 'lathe' driver as I want. > The problem I have is that the independent lathe driver doesn't have any > ramping capability and so, to get the lathe running, I have to wind the > multiturn speed pot right down, enable the driver, and then wind the pot > back up slowly to the speed I want - the stepper won't start on its own > at a high step rate. So, can anyone point me to some kind of suitable > circuit (schematic) for a ramping oscillator to feed in the step pulses > so that I can just turn it on at a preset final speed value and leave it > to bring itself up to speed or suggest some other way of doping this > thing? ( I wondered bout a PIC chip but I don't really understand them > well enough yet..) Thanks.... >
Is there any reason you aren't just letting EMC generate the pulses for both A-axis and spindle mode? Do you need a hardware step generator because software step pulses aren't fast enough for lathe mode? It would not be difficult to come up with a HAL configuration that uses two HAL stepgen modules, one in position mode for A-axis control, and one in velocity mode for spindle control. A limit2 block could be used to provide speed ramping in lathe mode. You could also use a single stepgen in velocity mode, with a PID loop for A-axis position control, and a limit2 block for speed ramping in lathe mode. In either of the above cases, a mux block or two would be needed for mode switching. Overall, I'd call it a "moderate" difficulty HAL configuration - definitely not beginner stuff, but quite doable once you have your head wrapped around how HAL works. If you can use two separate EMC configurations for lathe mode and A-axis mode (restart EMC when switching modes), it gets even simpler. Each config would load exactly the HAL blocks it needs, with no muxes. Regards, John Kasunich ------------------------------------------------------------------------- Sponsored by: SourceForge.net Community Choice Awards: VOTE NOW! Studies have shown that voting for your favorite open source project, along with a healthy diet, reduces your potential for chronic lameness and boredom. Vote Now at http://www.sourceforge.net/community/cca08 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
