Hello Guest it is July 17, 2019, 07:22:17 PM

Author Topic: Missing steps in Y axis only  (Read 8657 times)

0 Members and 1 Guest are viewing this topic.

BClemens

*
Re: Missing steps in Y axis only
« Reply #10 on: February 21, 2009, 11:56:22 PM »
Hello Chip,

OK, you cleared up another question mark. The shut-down by the G320 was witnessed. The paperwork for these 320's is around here somewhere but they were purchased in '03.

Thanks,
Bill C.

BClemens

*
Re: Missing steps in Y axis only
« Reply #11 on: February 22, 2009, 04:17:18 PM »
This is what Y did.....



BClemens

*
Re: Missing steps in Y axis only
« Reply #12 on: March 02, 2009, 07:19:38 PM »
Replaced failed (I thought) Y axis servo encoder, parallel port cable, tuned and tuned Y axis G320 - then tuned some more. Still missing steps in only Y axis, both other axis do fine. Continuous jog will work fine two or three times then do nothing except count the DRO - motor doesn't move then for no apparent reason begins moving. Happens both Y directions; + and -.

This is not making sense. The oscilloscope shows a signal from the computer during jog and into the Geko320 but this continues to occur. Should I replace the Gecko, the encoder again, the computer, my shop, wife, or just buy a bottle of Wild Turkey? This machine is all about getting it going and not doing anything. Anyone interested in a nice small NC machine real cheap?

Thanks,
Bill C.

Offline Chip

*
  • *
  •  2,057 2,057
  • Gainesville Florida USA
    • View Profile
Re: Missing steps in Y axis only
« Reply #13 on: March 02, 2009, 09:55:25 PM »
Hi, Bill

Is Wild Turkey strong enough, Swap your X & Y Gecko's around and test, If it stays with he Y axis, You need to look at the wire-ring carefully.

Post your Mach3Mill.xml file if that's the Profile your using, C:\Mach3\ folder, Make a copy rename it to Bill CMach3Mill.xml.

Is your scope hooked to the actual Gecko terminals, Common, step & dir.

Chip

Offline Chaoticone

*
  • *
  •  5,524 5,524
  • Precision Chaos
    • View Profile
Re: Missing steps in Y axis only
« Reply #14 on: March 02, 2009, 10:51:06 PM »
Bill, I had a problem with the connectors on a gecko once. Sounds similar to your problem. The wires were connected fine it was where the connectors made contact with the header pins on the drive. Maybe you can give it the wiggel test? Next time your jogging manually, try wiggling the black connectors on the gecko and see if it stumbles. I got lucky and actually saw it ark a couple of times.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

BClemens

*
Re: Missing steps in Y axis only
« Reply #15 on: March 03, 2009, 06:57:14 AM »
Chip, The scope probes are held on both the step and dir on the breakout board and the encoder feedback to the Gecko. I'll post the XML file.

Brett, Didn't think of that but that's a possibility since those connectors had to be wired separate of the drives in order to see what I was doing. I'll check that.

I also need to check two other things: to make certain that a motor drive voltage is getting to the brushes when this occurs - bad connection through the drive chassis plug (Molex) or a bad armature in the servo.

Also, I did swap the drives between X and Y but not totally. Only swapped the plugs at the connectors on the drive chassis - sort-of inconclusive. Will repeat that once more but totally by physically moving the 320 under the plug connectors. That may tell the most. But, I fear that the servo motor has a shorted winding which results in a dead spot if the motor happens to stop on the bad commutator segment. These were new motors but Y may have suffered an over heat a while back when the gibbs were too tight and a nylock nut allowed the ball screw thrust bearings to tighten to the stall point. That blew a 3 amp fuse (at 57 VDC) a few times. I may have cooked a motor. It's amazing how strong these motors are....and the 320 to drive them. The ball screw was hardly movable by hand when I finally realized the problem. But the motor had been doing fine until recently.....

Thanks for the help!
Bill C.
« Last Edit: March 03, 2009, 07:16:12 AM by BClemens »

BClemens

*
Re: Missing steps in Y axis only
« Reply #16 on: March 03, 2009, 07:59:27 AM »
Checked for voltage to the servo motor and it is not there when the motor stalls yet I see the step signal going to the 320 during the stall. Also noted that the signal in one direction when the motor is running is around +7 volts and about -1.5 volts in the other direction - the one prone to stalling the most. Narrowing it down to tuning or the 320 has bad drive mosfets in one direction (or both).

Bill C.

I'll go through the tuning again very carefully this afternoon.....Thanks again.
« Last Edit: March 03, 2009, 08:02:01 AM by BClemens »

BClemens

*
Re: Missing steps in Y axis only
« Reply #17 on: March 04, 2009, 05:36:33 AM »
Chip, what did the XML file show? I know it showed that I had been adjusting the settings for the MPG because of a calibration problem that I have been seeing. It was set for 4 per detent and it should have been 400 per rev, but...It actually should be 1 PPR - 100 per Rev. but cannot get the 1 pulse - it is always 4 or 5 and CNC4PC says this isn't right....Arturo is sending another MPG.

Too many problems here at one time - computer is freezing on start-up, crosstalk on new computer port pins, Y axis intermittent, MPG not calibrating correctly, 401K is still plummeting, etc, etc. The President is giving stock market advice... Having too darned much fun over here!

Haven't gotten to the tuning yet.

Bill C.

Offline Chip

*
  • *
  •  2,057 2,057
  • Gainesville Florida USA
    • View Profile
Re: Missing steps in Y axis only
« Reply #18 on: March 04, 2009, 04:22:08 PM »
Hi, Bill

Looked at your xml, In Motor-Tuning, Set the Step/Direction "Pulse's" to 5 and see it that help's, Gecko want's them at 3 or above, It gives them a little more time to see the step/dir. Pulse's.

Hang in there, In general I'm felling about the same way.

Chip 

BClemens

*
Re: Missing steps in Y axis only
« Reply #19 on: March 04, 2009, 05:18:59 PM »
Thanks for that setting advice Chip.

 I have something to be happy about - StarTech says send their PCI card back to them for replacement - "hardware issue". That makes me very happy - strangely happy. That's one down!

Bill C.