On Mon, 2011-02-07 at 13:01 -0800, Michael Jones wrote: > I am running a set of KL23H276-28-4B on a little Shereline CNC mill with EMC > running to a Geck G540 controller.
> I've noticed that after a while (even just sitting still with the machine > powered) that the steppers are very warm (I haven't checked actual temp > yet). They're not so warm you can't touch them, but not comfortable to hold > on tight for long (imagine the temp of a fresh cup of coffee in a paper > cup). > Is this "normal" should I be concerned. They don't seem to get any hotter > than that, running or standing still with power on doesn't seem to make a > difference. A stepper is full on all of the time, even at rest (unless your drive has a park current feature). What makes the motor move is a change in which coil is full on. The heat is a waste product and is similar to the heat given off from a resistor. The heat from a resistor is Watts = Volts x Amps = Amps^2 x Resistance. http://en.wikipedia.org/wiki/Watt As long as there is current going through the stepper motor, it will be giving off heat. I found on my test bench that the motor I was playing with actually gave off a lot more heat at rest. I believe this is because one coil is on full time, where as when the stepper is in motion, back EMF lowers the effective voltage, the steps have current gaps between steps, and the heat is spread over more area (two or four coils instead of one). I believe to keep from skipping steps, you want to drive the stepper as hard as you can. Usually, the limiting factor is heat. How much heat depends on the quality of the motor materials. The manufacturer may have a specification for the motor in question. If so, drive your motor so that it comes close to this temperature, but not over it for an extended period. A fan could be useful too, but you should have a temperature activated cut-out in case the fan fails. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ The ultimate all-in-one performance toolkit: Intel(R) Parallel Studio XE: Pinpoint memory and threading errors before they happen. Find and fix more than 250 security defects in the development cycle. Locate bottlenecks in serial and parallel code that limit performance. http://p.sf.net/sfu/intel-dev2devfeb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
