No movement on one axis

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15 Feb 2011 20:03 #7225 by sjcdcheu
I am not sure any other setup issue. The machine had been setup and under testing now. Also, I had setup the Halui for the HOME and START signal by the help of John.

However, I found sometime the step motor had been hang and not movement by using the jogging mode.

I just tested by a simple Gcode and run on the machine.

1. G20
2. G90
3. G64 P.0.01
4. G17
5. F10
6. G0 X2 Y-3
7. G1 Z-0.1
8. G1 X1.5 Y-3
9. G1 X1.5 Y-2 (stay at x1.5 and not move to x2 follow next step however, if I change the line 7 to G1 Z0.1 or without Z-axis movement and the program running smoothly)
10. G1 X2 Y-2
11. G1 X2 Y-3
12. G0 X0 Y0 Z0
13. M2

The information of the machine setting
EMC2 2.4.6 (Installed by using Live CD Ubuntu 10.04 and upgarded from 2.4.3)
Stepping motor kit with the driver card from Fireball.
Intel MB D945GCLF.

The hardware should be working fine and tested by using other CNC s/w.

Please help!

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16 Feb 2011 00:05 #7226 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Your acceleration might be too fast for your setup. Try reducing that and run the stepper test for each axis to verify your not loosing steps or stalling out one of the steppers.

www.linuxcnc.org/docview/html/common_Ste...iagnostics.html#r1_3

John

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16 Feb 2011 21:47 - 16 Feb 2011 23:07 #7263 by sjcdcheu
Replied by sjcdcheu on topic Re:No movement on one axis
John, I just found out that I need to set up the drive enable on parport pin 14, 16 & 17 for XYZ. So far, I have no problem for the movement.

But the way, I am using the PLC to control the CNC start and go home by Halui. I am just thinking to cut the power on the motor driver when idle or program complete. Every cycle, I will power up the driver card, go HOME and start the program. Do you see any problem or it will hang up.?

Thank & My Best Regards,
Dason.
Last edit: 16 Feb 2011 23:07 by sjcdcheu.

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17 Feb 2011 00:50 #7266 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
If you cut the power to the stepper driver you MUST rehome every axis not just go to home as the stepper can move without power and EMC will have no way to tell this.

John

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11 Mar 2011 14:15 - 11 Mar 2011 14:19 #7728 by piasdom
Replied by piasdom on topic Re:No movement on one axis
i ran this test a number of times and having trouble. the first part of the test, Z is correct. but in the second part of the test,i gain a about .002" after each run. i ran the test on all the axis and it's only on Z that i have this problem. this is a sherline mill with stepper motors running emc2.4.6.
i attached the ini file if needed.Thanks for any help.


[AXIS_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 0.335
MAX_ACCELERATION = 12.000
STEPGEN_MAXACCEL = 10.0000
BACKLASH = 0.000
SCALE = 16000.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -9.500
MAX_LIMIT = 9.500
HOME_OFFSET = 0.0

[AXIS_1]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 0.335
MAX_ACCELERATION = 12.000
STEPGEN_MAXACCEL = 10.0000
BACKLASH = 0.0000
SCALE = 16000.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -5.000
MAX_LIMIT = 5.000
HOME_OFFSET = 0.0

[AXIS_2]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 0.335
MAX_ACCELERATION = 12.0
STEPGEN_MAXACCEL = 10.0000
BACKLASH = 0.0000
SCALE = 16000.0
FERROR = 0.05
MIN_FERROR = 0.01
MIN_LIMIT = -5.0
MAX_LIMIT = 5.0
HOME_OFFSET = 0.0

File Attachment:

File Name: Axis-065e8...d15b.ini
File Size:2 KB
Attachments:
Last edit: 11 Mar 2011 14:19 by piasdom.

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11 Mar 2011 18:17 #7730 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
Try and lower the acceleration on the Z axis. It might be fighting gravity a bit too much and loose a step changing from down to up.

John

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13 Mar 2011 02:23 #7772 by piasdom
Replied by piasdom on topic Re:No movement on one axis
do i lower my STEPGEN_MAXACCEL as well ?

like;

MAX_ACCELERATION = 10.000
STEPGEN_MAXACCEL = 8.0000

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13 Mar 2011 09:06 #7773 by Rick G
Replied by Rick G on topic Re:No movement on one axis
From the manual..

"STEPGEN_MAXACCEL = 21.0 ( HAL ) Acceleration limit for the step generator. This should be 1%
to 10% larger than the axis MAX_ACCELERATION. This value improves the tuning of stepgenā€™s
"position loop". If you have added backlash compensation to an axis then this should be 1.5
to 2 times greater than MAX_ACCELERATION."

Rick G

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13 Mar 2011 19:19 #7784 by piasdom
Replied by piasdom on topic Re:No movement on one axis
if i understand this, i can make STEPGEN_MAXACCEL = 50.000 and MAX_ACCELERATION 1% to 10%
smaller; 47,500(5%). what do i use to get the max for STEPGEN_MAXACCEL ?

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13 Mar 2011 20:59 #7786 by BigJohnT
Replied by BigJohnT on topic Re:No movement on one axis
The maximum acceleration an axis can do is dependent on many things like stepper drive voltage, mass, friction, and gearing to name a few. For my plasma I found what acceleration was too much (stepper stalled) and backed off a comfortable amount and ran the stepper test several times to make sure I did not loose any steps. I did this until I found a good balance between speed and acceleration. For example my X and Y axis are set at 150 and my Z is set at 50 on my plasma due to gearing and other things. In stepper systems you have to find the balance between too fast (loosing steps) and too slow (speed drops on short moves).


John

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