Re: Re: need help emc backlash

Peter

Freqmod or steppermod? How many pulses per unit? Unit?

0.027's a lot to expect. Sounds like stock acme. You might read up on some
of the posts where people have done things like casting new nuts, using two
and a spring between, or splitting a nut and pinching the halves to get less
backlash.

EMC can do it but you will not get good contouring around the arcs where an
axis changes direction. Cutting forces will drive the axis ahead of
compensation.

EMC feeds backlash pulses in over a number of motion loops rather than all at
once but it is rather easy to run into following error problems if you have
not made provision in your ini to feed those extra pulses into the normal
axis pulse train.

I'd set MAX_VELOCITY in [TRAJ] a bit higher than it is set in any one [AXIS].
Then I'd start commanding circles at fairly low feedrates and watch the
motion when each axis changes direction. Make bigger differences between
these variables if you still get following error.

HTH

Ray

On Monday 01 July 2002 03:05, you wrote:
> Message: 24
>    Date: Mon, 01 Jul 2002 05:59:46 -0000
>    From: "armadhas" <peterh@...>
> Subject: Re: need help emc backlash
>
> jon
> the ammount of backlash is .027 new machine still setting it up
> peter
>
> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > armadhas wrote:
> > 
> > > hi
> > >
> > > i am having trouble with emc
> > > when the backlash amount is set in the axis setup
> > > the machine runs at the set feed rates but the backlash when
>
> tacking
>
> > > it up runs at full speed and it seems to make no differnce
> > > what any of the speed setting are set to in the emc.ini file
> > > it takes it out that fast it skips steps on the steppers
> > 
> > How much is your backlash?  I think the scheme used is really
> > only designed for backlash in the .001" range.
> > 
> > Jon