Harrison, I have new servo amps from Servo Dynamics in Chatsworth CA.

Got everything working today except I have a continuous chatter or low amplitude
oscillation in the x axis servo. What could be causing that?

Z and y axis are working fine as does the tool changer.

The knee goes up and down properly after I swapped one 3 phase wire.

Paul Lamar

-American Flyer wrote:

Paul,

Congratulations! It's a great feeling when you finally get to see the thing run.

I remembered that you mentioned having newer servo amps, but you might
very well still have the same power supply (or one with the
same or even higher voltage since the motors take 92V).

The oscillation could be a lot of things, but most likely the
adjustments on the servo amp are not right. Probably the "P" or
proportional gain constant is too high. I can't help much there since
I have different servo amps. It might not be an oscillation at
all, but rather a constant AC signal being applied to the servos as a
result of some problem on the resolver logic card in the
Bandit. That is the card which I had to repair in my mill. Does the
frequency of the apparent oscillation ever change? If so then it
probably is a true oscillation.

The frequency seems to stay the same. It comes and goes when I move other
things around and it almost dies down sometimes. I have the manual
on the servo amps as I stopped in at Servo Dynamics and they gave me a copy.
I'll give the gain a try tomorrow.

I had the same problem with the knee when I first hooked mine up.
Do you have actual 3 phase power available, or are you using a
rotary phase converter as I am?

Harrison Young

I have 3 phase power in the hangar.

Paul Lamar

American Flyer wrote:

Paul,

You could also try swapping things around between different axis. 
I did that while troubleshooting my machine. If you want to swap
servo amps, just be sure to swap both the drive from the Bandit 
AND the resolver feedback from the motor back to the Bandit (but
leave the motor drive and tach connections connected to the same amp). 
This test is one of the easiest to do, and should narrow the
problem to either the servo/motor set or the Bandit as being the problem area.

Harrison Young

Thanks Harrison

Paul Lamar
 
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