Re: Lost steps

Had another half hour to tinker today. In answer to recent postings
about ground wiring I find that I did in fact wire the grounds in the
way you all are suggesting. All the 37 V grounds come from the neg
post on the capacitor, all the 5V grounds come from a common point on
that little board.

But let me relate a couple things that happened a few moments ago. I
decided to try running the motors faster. In the EMC "midi mode" I
punched in a 2" move at f8. The move was apparently perfect.I tried
f10, again apparently perfect. F7 yes. F6 no, many lost steps. F12
the
motor just buzzed.I repeated the f8 moves at least a dozen times
without an obvious lost step.
F7, if I understand EMC right, would be 933 half steps per second,
way
beyond what someone said, would be resonance.

What's happening? I can't always machine between f7 and f10!


Additionally:
In fooling around and changing motors I found that if I turned off
the
driver with EMC still running, changed motors plugged into the Y
axis,
for instance, turned the driver back on, the motor did not lock and
would not move until I rebooted EMC, not the computer just EMC.
Can someone explain.

My thought on the shielding thing, was that I would take the X axis
board out again, remove the db25 junction board from the case and
string the whole thing out with 6" between each piece and twisted
leads on the power and signal lines, and see how it acts that way.
With the controller board in the case, it is only an inch from the
transformers, the wires to the on/off switch are about 3" above the X
axis board, and the signal, power, and motor wires all cross at one
place or another.

Any thoughts?

Jerry

--- In CAD_CAM_EDM_DRO@egroups.com, Jon Elson <jmelson@a...> wrote:
>
>
> Mariss Freimanis wrote:
>
> >
> >
> > What may be overlooked here is the intermittent nature of the
problem
> > originally reported.
> >
> > If you don't want to have a system plagued with noise problems, do
> > the ground wiring right from the beginning. Right means use the
> > concept of a "holy point ground". This means ALL ground wires are
> > returned to a single point; power supply ground, motor drive
ground,
> > parallel port ground, in short if it has a ground wire, take it to
> > that point! If shields are used, take them there too.
>
> This is not always the best solution. For power wires, however, it
is
> almost
> ALWAYS the best way to do things.
>
> > Resist the temptation to "daisy chain" ground wires. It can be
> > tempting to run a 3" wire from one device to an adjacent one where
> > otherwise it would be a 3 foot wire run back to the "holy point"
You
> > won't be doing yourself a favor by taking the shortcut.
>
> Yes, this is a very good way to get these circulating currents, also
> known as
> ground loops.
>
> Jon