Re: Freqmod problems

[rehenry <rehenry-at-up.net>]

Erie

Hey I wonder if the following error problem with freqmod is related to 
the notion that we have explored before that if you run at the max, 
during accel you pile a few pulses into the following error buffer that 
can't get put back into motion.  You might try setting

[TRAJ]
...
MAX_VELOCITY =          1.67

a little larger than 

[AXIS_0]
...
MAX_VELOCITY =                  1.2

for each axis.

You should also set 

DEFAULT_ACCELERATION =  20.0
MAX_ACCELERATION =      20.0

much lower than default.

HTH

Ray



On Tuesday 12 February 2002 09:11 am, Shelbyville Design & Signworks 
wrote:
> specifics:
>
> Gantry router, 8' x 12' work area
> rack & pinion drive
> 23 frame stepper approx 200 oz-in or so, running halfstep, geared 40:1
> with a 24 d.p. 30T pinion
> (step size is about .00025, way to small for routing, but this project
> started out with a real small
> budget (wife holds the purse strings and we all know how that goes) and
> the reducers were already on the machine)
> gantry weight is approx 600 lbs +-
>
> (if you've ever seen a Heath/Esab plasma cutter, it's the same machine)
>
> running the table on Turbocnc I can achieve 150 IPM easily,
> but no contstant contour.
>
> I am going to be removing the gear reduction and going to gecko 201
> drives, with a 550 oz-in
> motor on the x axis, dirctly driving a 20T pinion, it will increase the
> step size to approx .0015, this should
> help with the speed, but the biggest problem is inconsistent step
> pulses (scope confirms this)
> with this much inertia, it doesn't take alot to throw things out of
> whack.
>
>
> erie patsellis
>
>
>
> Shelbyville Design & Signworks
> 1309 W. S. 7th Street
> Shelbyville, IL 62565
> (217)774-4444
> visit our website at http://216.43.233.169
>
> ----- Original Message -----
> From: "Hugh Currin" <currinh-at-oit.edu>
> To: "Multiple recipients of list" <emc-at-nist.gov>
> Sent: Monday, February 11, 2002 6:23 PM
> Subject: Re: Freqmod problems
>
> > Erie:
> >
> > What type of machine are you using?  i.e. size steppers and drivers.
> > I'll
>
> bet
>
> > someone on the list has an *.ini file they'd be willing to send you
> > as a starting point.
> >
> > I have freqmod working with 760 oz-in motors, Camtronic drivers half
> > stepping, 2:1 reduction timing belts on a bridgeport kneemill size
>
> machine.
>
> > Does this come close? It isn't optimum but may be a starting point.
> > :-)
> >
> > Hugh Currin
> > Klamath Falls, OR
> >
> > On Monday 11 February 2002 04:03 pm, you wrote:
> > > am I the only one who has unsuccessfully tried to use
> > > freqmod with steppers? no amount (I've spent at least 8
> > > hours on this so far) of pid tuning seems to eliminate following
> > > errors. Steppermod.o for now.
> > >
> > >
> > > erie patsellis