Re: Question regarding Tuning Servo motors

--- 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