Ian, You Wrote:
"I am using a motor of indeterminate voltage (no plate on it) but which I think is probably about 4.5 - 5 volt and I am driving it with 12 volts. At this I can get a fair speed out of it but, having read another post on this list which recommended using the highest voltage possible with an Allegro driver, which is what I have, I tried upping the voltage to 24 volts. The motor slowed down and won't go at more than 2/3 the speed at the lower voltage. Anyone know why this is? From all I have read in the past, I thought more voltage was better.." Driving steppers with more voltage does not necessarily equal better performance. If you are driving a light load, the "Cogging" of the steppers can introduce oscillation during the step and cause missed steps. There is a "Sweet Spot" based on load, inertia, acceleration and operating voltage. In my case 12 volts works way better than 18 or even 24 volts. I used a bench power supply on my setup and varied the motor drive voltage while running. You could literally hear the difference in the moves. Each machine will behave differently. There is no one set of settings that will provide the best performance. Even using a micro-stepping motor driver may not be the best solution. I found that a micro-steppping motor driver was taking 980 microseconds to a actually move from one "step" to the next. I then switched to a simple chopping driver with no micro-steps, and let HAL do the work. HAL was capable of driving steps well up into the 50 microsecond range. With proper acceleration settings, I get plenty of speed and no missed steps. Jim ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
