Question tuning G320 servoamps.

Hello all,
I turned on my G320's last night and was playing around optimizing
the settings. I'm not sure that I have a concise question, but I
thought I'd share what I'm seeing so that others who might have had
the same symptoms might comment.

Some background : I am using some leeson 1/8HP DC motors with
USDigital 100cpr encoders. It will hook up with a 2-1 reduction to a
10tpi leadscrew on my 3-1 machine. So, there are 8000 counts per
inch which in theory will get me roughly 60ipm with Master5. The
power supply is a Camtronics.

First, is it realistic to try to setup the servos with no load
attached? It seems to me that the load of the lead screws will
significantly affect the dynamics of the feedback loop (i.e. it will
change the transfer function and therefore the step and impulse
responses significantly).

Keep in mind I've just gotten started dialing them in and haven't
attacked it with my Oscope yet. I didn't get it wired until about
2am last night.

I'm noticing that when I give a jog command in Master5 that when
the servo is accelerating it sort of does it in fits and starts. It
basically starts moving then violently stops then continues
acceleration. It does this a couple of times before it reaches
speed. I suspect that it is the acceleration profile that Master5 is
outputting. It seemed to get slightly better as I lowered the
acceleration rate from Master5. Adjusting the gain and damping had
some effect but even at the minimum settings it still diplayed this
symptom.

When it is up to speed it is smooth. Tonight I will break out the
scope and look for things like voltage droop on the input voltage
line, and try to get a feel for what the pulse stream looks like. I
played with the Master5 clibration tool, but I think I really need
the whole machine hooked up for that to be useful.

The settings I had for the motor were : max speed 1IPS (8k pulses *
8PPI), and accelerations ranging from 0.1 -> 1.0 IPS^2. I sort of
think it has something to do with the pulses coming out of Master5.

I'm seriously starting to consider just building a DOS machine and
using one of the dos only gcode interpreters. Possibly even using
EMC so I can transfer files over the internet.

I'll search through the archives for info on this, but if it sounds
familiar to anyone let me know.

Thanks in advance.

-Erik Reikes