If they have tail shafts, cheap encoders from US digital mounted on the back of them are the best solution.You can tie the f-error back into linuxcnc so you know exactly how much error has accumulated and can fault if its too much.
I've gone through this very thing, and ultimately went to servos. However steppers with encoders served me very well for a few years and made me profitable enough to afford the luxury of servos. The encoders helped save me many times the cost of them, over the money I would have lost in scrap parts. The effects of missed steps become larger on longer programs, or running the machine without homing it for many days. I imagine on even a perfectly running stepper machine, eventually its going to miss a step, and I found for me it was usually due to a specific combination of movements of a program that would cause it. Once you program enough parts, it will eventuall find that combo that causes missed steps, and you won't know it can happen until it does. -Curt On Fri, Jul 24, 2015 at 6:36 AM, John Thornton <[email protected]> wrote: > The maximum velocity depends on the voltage and as Jon said testing for > lost step is needed. > > For example look at the torque vs speed charts here > > http://www.automationdirect.com/static/specs/surestepmotors.pdf > > Also on the wiki is some formulas for steppers > > JT > > On 7/23/2015 7:42 PM, Tom Easterday wrote: > > I am tweaking my Emco 120P lathe that is driven by Berger-Lahr 5-phase > stepper motors and Oriental Motor Vexta UDX5128NA drivers. Step/Dir is > supplied by a Mesa 6i25. I want to know what maximum velocity I can > reliably get from the motors. I have run them at 90ipm max for some time > and have never had a problem. But we want to do some movements that > require higher speeds (140-150 ipm) and I am wondering if I crank up the > step pulses can they handle it. > > > > I turned up the parameters in my .ini file in order to step at 150ipm > and I get what I think is good movement. I moved around randomly and also > in specific increments and don’t see any error on the DRO. What tests can > I do to verify that the machine can RELIABLY handle this speed? > > > > The relevant section on the step/dir timing from the Vexta driver > manuals are here: > > http://bgp.nu/~tom/pub/vexta-1.pdf > > and > > http://bgp.nu/~tom/pub/Vexta-2.pdf > > > > > > My current .ini settings are: > > > > [DISPLAY] > > MAX_LINEAR_VELOCITY=2.5 > > > > [TRAJ] > > MAX_VELOCITY=2.5 > > > > [AXIS_0] > > MAX_VELOCITY=2.5 > > MAX_ACCELERATION=50 > > STEPGEN_MAXVEL=3.125 > > STEPGEN_MAXACCEL=62.50 > > DIRSETUP=10000 > > DIRHOLD=5000 > > STEPSPACE=5000 > > STEPSPACE=5000 > > STEP_SCALE=10159.997 > > > > > > AXIS_2] > > identical to AXIS_0 (except for “-“ on STEP_SCALE) > > > ------------------------------------------------------------------------------ > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
