Re: Question regarding Tuning Servo motors

Dan and Tom, Thanks for your replies...

The rate multiplies on x and y were set to 1X and ran well.

The rate multiplier on the z was set at 1X but would not work until I
changed it to 2X.

The max RPM on any of the motors is less than 100 RPM.

Just how far from the power cable should the encoder cable actually
rest? I'm using very good shielded multi conductor cable for the
encoders...each pair of wires is shielded and then the entire bundle
of 5 pairs is also shielded...

We are still getting spradic faults...and sometimes it's on a Gecko
other than the one we are running during the test...any ideas on this
front?

Thanks Again,

Preston

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "caudlet" <thom@...> wrote:
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dan Mauch" <dmauch@> wrote:
> >
> > You are using the G340 with the rate multiplier. The problem may
be
> that you have too high a setting of the rate multiplier which could
> cause the G340 to fault sooner.
> > Most gecko drives are properly set from the factory for the Gain
and
> the Dampening. I generally set them for at 11:30 from the fully CCW
> position when looking at the back of the G340. I have set hundreds
of
> motors this way and they work fine with very minor tweaking.
> > Other things to look at is that you may have the acceleration set
> way to high.
> > With those motors, I would take the current limiting trim box and
> turn it CW all the then back off 1/4 turn.
> >
> > Dan Mauch
> >
>
> Dan is right. The G340 is a G320 with a plug-in step multiplier
card.
> It's intent was to provide more steps to the Gecko because PC's
were
> limited to the number of steps per second they would generate.
> Earlier this year MACH increased the number of steps from 45,000 to
> 100,000. You only need the step multiplier if your mechanics need
the
> full 3000 RPM out of the motor and/or you have high count encoders.
> At 250 counts (1000 pulses) per rev your max number of pulses need
to
> get the full 3000 RPM is only 50,000 per second. You can easily get
> that from most pulsing software controllers.
>
> Pulse multiplication should not be used unless you have to have it.
> It reduces your resolution and changes the dynamics of the tuning
> somewhat.
>
> Are you belt reducing the motors to gain more torque? If you have
the
> normal 5 TPI ballscrews then you probably don't need the 600 IPM
those
> motors could provide. Using a 3:1 or 4:1 you gain torque and
> resolution and lower the max speed to 200 or 150 IPM respectively.
>
> On a big mill the torque to move the table is important not to
mention
> pushing a bit through steel.
>
> You may find the acceleration settings in the software need to be
> adjusted when you get the motors on the mill.
>
> You can do preliminary tuning on the raw motors but only after they
> are loaded can you do "perfect" tuning (then again perfect is not
> normally needed). If it's touchy unloaded, you need to find the
root
> of that problem. We sell the Gecko 320 drives and the 72VDC 850 oz-
in
> (peak) in our RouterPaks and PlazPak products so we do through
> hundreds of setups a year. The motors are stable across a wide
range
> of Gain and Dampening settings on the bench. We tune them by ear
> (once youhave heard a properly tuned set "Sing" you can do it with
> just a screwdriver and your ears).
>
> Keep your encoder wires away from any power wires to the motors or
any
> VFD leads. If you have to run more than 6 or 8 ft from the motors to
> the drives then consider using a differential driver/receiver
> (powered) cable.
>
>
> TOM CAUDLE
> www.CandCNC.com
> Totally Modular CNC Electronics
>