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Author Topic: servos not traveling proper distance, new install of 2.0  (Read 7782 times)

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Offline fdos

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Re: servos not traveling proper distance, new install of 2.0
« Reply #10 on: May 08, 2007, 04:33:06 PM »
OK thats good information

Sounds to me like you have a noise issue, either getting into the Step input on the drive or the encoder cables.

Brushed spindle motor?   Could be brushes arcing a lot.

These noise issues are the reason I like to use differntial signals for both encoders and Step/dir signals.

In retrospect with this new information it's unlikely to be drive tuning.

Wayne.....
Re: servos not traveling proper distance, new install of 2.0
« Reply #11 on: May 08, 2007, 04:34:11 PM »
You have an encoder noise problem :( Do you have a scope to test with?
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: servos not traveling proper distance, new install of 2.0
« Reply #12 on: May 08, 2007, 04:38:56 PM »
Ok so if it is noise, how do I verify that. The only thing I have is a multimeter which I don't know if that will work. I don't know what a scope is.
Should I try moving the gecko box to a different location, or maybe re route the wires?
I made the wires my self and they are just wrapped with electrical tape.

Offline fdos

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Re: servos not traveling proper distance, new install of 2.0
« Reply #13 on: May 08, 2007, 07:45:45 PM »
first just try to determine where the noise is coming from.

Try running your program without the spindle running.

Is this a router?

Wayne....
Re: servos not traveling proper distance, new install of 2.0
« Reply #14 on: May 08, 2007, 08:24:41 PM »
The servos are actually loosing steps when I run them with out the spindle powered up. I wrapped the cables in foil and I can see a difference while running a program with the spindle powered and spinning. The servos dont move as much. Still though there is something causeing the servos to move even when the spindle is powered down.
On a side note, the computer looses time when Im running Mach 3. If I run a 20 min program the clock is 20 min slow.

Up untill 3 days ago everything ran perfectly for over a year.
If this were a new build I can understand tweaking required.
Re: servos not traveling proper distance, new install of 2.0
« Reply #15 on: May 09, 2007, 10:36:36 AM »
is there a way to track down the noise source?

Offline fdos

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Re: servos not traveling proper distance, new install of 2.0
« Reply #16 on: May 09, 2007, 12:58:54 PM »
Easiest way to find source of noise is to eliminate it by switching off electrical items which may cause interference.

Is there anything that may have changed recently?  Have you checked the condition of your encoder cables?   Look them over very carefully, ensure you still have good grounds without ground loops.  If in doubt try another cable.

Wayne....
Re: servos not traveling proper distance, new install of 2.0
« Reply #17 on: May 09, 2007, 05:37:17 PM »
I know it is coming from the computer, because I called Gecko and they told me to unplug the printer cable and see if the problem went away.
So I did that and the movement stopped right away. They told me to reformat the hard drive and install windows again. So I did that and when I turned the servos on and ran the spindle there was no movement so I figured the problem was solved.
When I installed Mach 3 the problem was back and just as bad as before.
There has got to be something to do with Mach 3 since it only happens when Mach 3 is on.
Over 20 lines of code the machine looses .25" on all axises.
I ran the motor tuning utility and it is not accurate. I told it to move 1 inch and it moved .995. Then it adjusted the motor steps to compensate and when I jogged the axis to zero it only went to -.086.
This is all 3 axises and the likely hood that all 3 cables, servos or geckos to fail at the same time is so remote.
I know there is no noise because the servos sit still when the printer cable is unplugged. When the printer cable is plugged in, the servos start to move, when the spindle is turned on they move faster. When the printer cable is unplugged, and the spindle is turned on, the servos dont move.

So what is next?
Rob
Re: servos not traveling proper distance, new install of 2.0
« Reply #18 on: May 09, 2007, 05:55:11 PM »
I just ran a experiment to verify the source of the problem
If the spindle is running and the printer cable is plugged in the servos move at approx .001" every 10 seconds
If the spindle is running and the printer cable is un-plugged the servos do not move

This experiment was done with nothing running on the computer. So some how the computer is sending a signal to the printer port even though mach 3 is not on. However I ran this experiment before I installed mach 3 and the servos did not move, so by installing mach3 there was some change done.

When the same experiment is done with mach 3 running, the servos move 3-4 times faster.
Re: servos not traveling proper distance, new install of 2.0
« Reply #19 on: May 09, 2007, 07:19:03 PM »
could the parallel port is bad?
I tried switching the bios to all the different parallel port configurations, but none fixed the problem.