On Sat, 10 Jul 2010 10:37:00 -0500, "Pete C."
wrote:


Ignoramus30064 wrote:

On 2010-07-10, Gunner Asch wrote:
On Sat, 10 Jul 2010 01:45:39 -0500, Ignoramus30064
wrote:

... Because it "creeps".

I have only one axis (x) wired right now. When the drive is powered on,
but with no input signal, the table imperceptibly slowly creeps. I
only noticed it because some tools fell off the table as it moved by
perhaps 8 inches in an hour.

There is a "test/offset" pot on the board that, if turned properly,
shifts input signal and makes the table move. I could easily set it so
that the mill does not _visibly_ move. I have not, however, been able
to get rid of the slow creep.

I may call AMC on Monday to find out.

i

Either you have voltage on the input (1-10vt) or you have rate
gain/test offset set too high. Test your input on a millivolt scale and
see if there is a trickle of power getting to the servo. Sounds like
there is. Might want to put in a 100 ohm resistor or something to get it
down to nada. If you have a scope..check it for trace AC as well. it
should be clean DC coming in...or nothing at all. If you have a leaky
diode..you might be getting a trace of AC or flutters.

I use a lot of AMCs on OmniTurn cnc lathes..but dont want to compare
them with mill uses.

Maybe it is a gain issue.

There really is no input: I use a reversing Lego switch to send signal
to from a little power supply to the amplifier, and the switch was off

i

Adjust your test / offset to get the minimum creep when the control
input is grounded to ensure it is not "floating". The little bit of
creep you may have left *may* go away once you adjust the gain when
tuning the servo loop, but it isn't important. You can not tune the
drive in any meaningful way unless it is operating under control of the
servo loop with the encoder and control PC.

Indeed. I wasnt aware he was free running the amp, without the control.

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch