American Flyer wrote:
Mark,
The problem with the Geckos only being rated for 80V is not so much that
we couldn't use full 300IPM speeds, it's that the power
supplies in our mills produced in excess of 100V. The Geckos can't
take this as an input which means we would have to come up with a
way to supply only ~70V at ~40-60A (at this point I'm assuming
that Paul's mill and mine have identical servo power supplies). The
motors are actually rated 92V.
The servo drivers on my mill are working fine, but are the old
original ones which PWM at about 5KHz. They squeal, and being 20
years old it is questionable how well they can be supported when
they eventually break. Regardless of which USB controller I end up
using (my own or the G2003), I think I'm going to put Rutex servo
drivers on my mill. Since they are rated at 200V, they will be in
no danger of damage from the 100V+ supply input, even if the power
company decides to send some bonus volts. The Rutex also have the
nice feature of being able to software adjust the PID settings
via an SPI port. With the right software, the PID alignment could be
completely automated.
By the way, I've been running my mill at 300IPM (no cutter)
to see what it's like. It's easy to envision major carnage if anything
goes wrong at that speed.
Harrison Young
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
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