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Author Topic: Jerky movement running code, but jog is OK!  (Read 1530 times)

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Offline PaulWC

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Jerky movement running code, but jog is OK!
« on: July 14, 2015, 08:17:43 PM »
I have a client system running Mach3 on a router:

32 bit Windows XP SP3
On-board parallel port
PMDX boards interfacing between PC and OEM controller cabinet
Stepper motor/ballscrew axis drives

Problem: After a 4 month period, trying to run previously proven code, the machine axis moves are jerky when running code, but move normal in jog mode.

I have read various threads with similar symptoms, and have applied, or checked for the many solutions presented in those threads... with no improvement on this system.

Items checked:
CV-Exact Stop, and Look Ahead setting in Config (no change)
G8 entry in code (none present)
G1 after previous G0 (correctly placed in code)
Motor tuning Vel and Acc set correctly for previous proven code runs
Driver Test reports System Excellent
Re-installed most recent Mach3 release

Initialization in code:
G20G64G17
G90
G91.1

Non of the equipment was powered up during any storms/blackout/brownout

Attached are the .xml, and a video of the X-Y axis jerkiness while running code

I have run out of ideas for checking a system that ran fine the last time it was powered up.

Any help ideas will be tried quickly and results reported back here.

Thanks, Paul

Offline derek

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Re: Jerky movement running code, but jog is OK!
« Reply #1 on: July 14, 2015, 09:26:28 PM »
When you run the code is the feed rate the same as the jog speed? Sometimes a machine will be binding at low speeds but seem to be fine at a higher rate because the speed increase gets above the chug.

That wasn't very eloquent but I'm sure you get my meaning:)

Offline PaulWC

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Re: Jerky movement running code, but jog is OK!
« Reply #2 on: July 14, 2015, 09:41:46 PM »
Presuming the jog speed is the same as Motor Tuning Velocity Speed... yes, the code feed rate is the same (190 ipm).

Offline PaulWC

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Re: Jerky movement running code, but jog is OK!
« Reply #3 on: July 15, 2015, 08:33:44 PM »
Problem Solved!

Miscommunication about the "CV FEEDRATE" button on the Settings Screen... Turns out it actually had been set.

The onsite operator re-checked the setting, and turned it off.... system runs as it should!

He turned it back on to verify it was the source of jerkiness, and proved it was!

Thanks, Gerry (CNCZone - ger21) for the directions he followed to resolve this issue.

Paul