RE: [CAD_CAM_EDM_DRO] Lost Steps (Me again)

Excessive acceleration definitely could be a problem. I've tweaked
stepper-driven linear slides on special machines I've built, and when I hit
the limit, I lose more than just a few steps. It seems like the motor
completely disengages, because there's noise, but nothing's moving. It
seems that losing only a few steps at a time would mean you're RIGHT on the
limit. What's everybody's experience on hitting that max-accel/max.
velocity limit?

Carlos

> Ozzie@... wrote:
>
> > Thank you all for the mountains of thought and communication on my
> > problem in setting up my Shoptask CNC.
> >
> > I tested to the best of my ability nearly all the suggestions,
> > testing
> > mosfets, turning down current, grounding and regrounding, re-routing
> > wires, changing wire sizes, twisting wire pairs, but none of those
> > things would make my little motors run without losing steps.
> >
> > Then Alan Rothenbush nearly insisted that I try changing software and
> > create a bootable disc with CNCPRO DEMO on it. It works! It works! No
> > question about it, it works! As far as I can see it works perfectly.
> >
> > Thank you all and thanks to this site. So glad it's here! Special
> > thanks to Alan.
> >
> > So because I'm never totally satisfied, what was/is wrong with my EMC
> > setup???
>
> Well, there is a chance it is the acceleration parameter. That is
> always very high
> by default, and needs to be turned down quite a bit.
>
> Here is a snip from an old .ini file :
> [TRAJ]
>
> AXES = 3
> ; COORDINATES = X Y Z R P W
> COORDINATES = X Y Z
> HOME = 0 0 0
> LINEAR_UNITS = 0.03937007874016
> ANGULAR_UNITS = 1.0
> CYCLE_TIME = 0.005
> DEFAULT_VELOCITY = 0.75
> MAX_VELOCITY = 1.75
> DEFAULT_ACCELERATION = 2.0
> MAX_ACCELERATION = 2.0
>
> I think this acceleration parameter will make it take one full second to
>
> accelerate to 120 IPM (although that would be above the max vel
> parameter). What is your acceleration set to? (I'm not sure which
> one actually controls acceleration.)
>
> Jon