Servo faults are showing up again

[bgolash]

Hi

I thought I had my problems with servo faults solved. Art had
mentioned to set Mach3 to sherline mode. That seemed to end the errors
on the X axis servo. Just to play it safe I ordered shielded and
twisted paired cables and line drivers from US Digital. Now that I
have the cables and driver installed for the x and z axis the x is
faulting again. It always seems to be the direct drive servo on the x
and never the z. I have the Rogers machine encoder interface card so
it will stop the machine if the following error gets too large. A few
weeks ago I was cutting a 3D part at 100 ipm with a following error
set to .005. Now I have the following error set to 1 inch and the axis
faults after it moved .5 inches.
I`m lost.

Barry

[wildcat]

I wish I could answer your question but I can't. It does sound like you have some ideas that are very interesting though. Could you describe your setup a bit more? What is this encode card you mentioned? What does the Sherline mode of Mach do? Should everyone who is running servos have that set? It is really neat that you have an idea of when the machine is off the required accuracy and stops.

[liston336]

bgolash,
I am not familiar with the set up you are speaking of, but i have
repaired/troubleshot a few cnc machines. It sounds like your machine is scewing for some reason. Does your machine have a master/slave setup
or is it a cantilever type(1 x axis or 2 x axises). Check your drive motor(s)
feedback (counting,pulses etc.)to see if maybe you are missing a signal.
Besides that look for a mechanical problem( pinion teeth, socket/belt slipping.
Since I'm not familiar with your machine I would need more info. Hope this is a little help. Liston336

[hightekmodels]

I spent a half day trying to find out why my CNC in Y was skipping a palts.
I could not see any thing. I finely put some WD-40 on it and the problem went away. Made me "mad". Well, such as home prew CNC's.
God bless

[DennisCNC]

you describe your setup a bit more? What is this encode card you mentioned? What does the Sherline mode of Mach do? Should everyone who is running servos have that set? It is really neat that you have an idea of when the machine is off the required accuracy and stops.

He is talking about this:
http://www.rogersmachine.net/encoderinterface.html


Barry,

You are scarring me I bought the card also will have my router ready for testing in a few weeks.

You mentioned direct drive servo on the X, maybe it pulls enough amps to cause EMI interference.
Do you have Geckos?

[bgolash]

Hi All

I`ve still had a difficult time with vibration on the x axis servo
and faults that occurred at slow jog speeds. I contacted Marisss and
he suggested the 3 changes below. I`ve just done the changes and the
x is acting normal. No more strange vibration and x movement on its
own. Without jogging the axis it would move in short moves repeatly.
So, for what ever reason bypassing the interface board seems to
solve the problem on the x axis.
I still have the z on the Rogers Machine encoder interface card and
it works perfect. The only difference I see is the new encoder wires
are now grounded to the G320 instead of the interface board. I wonder
if noise was a issue before.

(1) Connect the encoder directly to the G320. When you do, remove
the 470 Ohm resistor. This is to eliminate any adverse contribution
from the encoder board while you troubleshoot. With the encoder
interface card the wires from the encoder were going to the
interface board and then to the G320.

2) Set GAIN and DAMP to the 11 o'clock position (a little less than
half-scale). Set LIMIT fully clockwise.

3) DO NOT keep increasing the fuse size. You will eventually find
one big enough to blow up the drive if you do.