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CNC stalling on long moves
« on: May 16, 2020, 03:03:01 PM »
I have a 6040 CNC mill running stepper motors and MACH3.  Running since 2016.  Last week all was ok cutting production parts.
All parts passed inspection.
This week having problems that are NOT Mach3 related but I think I'll need Mach3 help with settings to help isolate the problem.
WIN7.  USB port

Park is back left of the machine.
0,0,0 is front, left, top of the material. 
If I jog the unit using the keypad and the jog rate is set to 50%.  I can move about just fine.
If I load a program and tell the machine to go to zero the y move comes up short.  Should be about 24" but is 3,5,7" approx short.
MACH3 thinks y is at zero.  X and Z have no problems.

This problem can also comes up running a program.  Some long moves are from the back of the material to the front.  And same short moves take place.

It appears like the stepper is stalling and then MACH3 says we're done with the move.  So several seconds on moving never took place.

I believe it's a stepper motor issue.  What setting in MACH3 could affect this situation. 
Slow everything down and see what happens?
Are there any internal feedback options that would get in the way.  Monitor on velocity?

Any troubleshooting suggestions.
« Last Edit: May 16, 2020, 03:04:52 PM by gmm50 »

Offline Graham Waterworth

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Re: CNC stalling on long moves
« Reply #1 on: May 16, 2020, 05:58:00 PM »
I would swap the x and y stepper driver and see if the fault is then on the x if it is its driver related if not it is axis related so could be the motor or maybe the rails are dry or sticking.

Without engineers the world stops
Re: CNC stalling on long moves
« Reply #2 on: May 16, 2020, 07:40:40 PM »
Good plan.
The Y makes long moves 24" and the x is only 9" or so.
Easy to swap and test.
Report tomorrow.  Good stuff
Re: CNC stalling on long moves
« Reply #3 on: May 17, 2020, 01:51:46 PM »
The material we work witn is 9" in x and 24" in Y. 
I swapped the X-Y cables going into the control box and then very carefully.................
I set ZERO then moved about in X and Y using the up down keys on the Keyboard.  I moved around the working area.  No problems
My jog rate was increased to 100% and again no problems.

I swapped the X-Y back and started to run test programs.  Cut small holes at the front of the material.
So big move from park to 0,0,0.  Run the code and then big moves back to Home. 
This is exactly where I observes failures yesterday.

I suspect Y axis (long axis) had resistance in the mechanism.  DIRT!!  Now it's cleared.
Running a big test (4 hours) next and then will tip the machine on it's side and do major inspection and cleaning.
We exclusively cut HDPE.  So lots of fine dust like shavings.  I thought we were good about keeping everything clean.

Thank you for making me think about things form a different perspective.

Re: CNC stalling on long moves
« Reply #4 on: May 19, 2020, 03:35:21 PM »
I was able to spend more time on this problem.
If I increase the jog speed to 100% I can get the Y axis to fail on long fast moves.  X never fails.
At 50% Y never fails.
The failure is axis stops moving but position keeps incrementing or decrementing/

If Y swap X and Y output from the controller, Problem is now on X output from Controller to Y stepper in machine.

Placing everything back to normal.  And reduce Y jog to 50% same problems but fewer.
Reduce Y jog to 30% no problems.

I'm suspecting lubrication is needed.
Re: CNC stalling on long moves
« Reply #5 on: May 19, 2020, 03:36:10 PM »
What type of lubrication does everyone use on lead screw and ball sliders?
Re: CNC stalling on long moves
« Reply #6 on: May 19, 2020, 07:05:21 PM »
I went to the hardware store and bought 'Blaster Dry Lube' for the rails (2) mostly teflon
'Blaster Graphite Dry' for the lead screw.

Applied waited to dry, then ran back and forth.
Did this 3 times.

During this process The stalling in the Y axis moved to a lower and lower speed.
Then got better and better.  At the end I eliminated the stalling and 100% jog type moved.
So Machine needed lubrication and perhaps more.
Re: CNC stalling on long moves
« Reply #7 on: May 20, 2020, 04:11:35 PM »
Conclusion......Lack of proper maintenance

After applying dry lubrication on the 2 rails and lead screws and running it back and forth manually.
Everything is resolved.

Not enough lubrication on our (my) part.
The plastic makes small chips and also a fine dust.  Living i the high desert we get big temp swings
30F at night 80+F midday.  We hadn't done much running for the past 7 months.

All this just make the Y axis fail.

Up and running now.
Thanks for your support.