stepConf and actual running precision issue

After another round of trying to correct the machine.

this time i will write down all the settings and the issues I face too

StepConf :-
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Base Information
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Machine Name : my-mill
Configuration directory : ~/linuxcnc/configs/my-mill
Axis Configuration : XYZA
Reset Default machine units : mm

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Drive characteristics : (multiply by 1000 for times specified in us or microseconds)
Driver type : Other
- Driver Timing Settings
Step Time : 3500 ns
Step Space : 3500 ns
Direction Hold : 5000 ns
Direction Setup : 5000 ns

o One Parport

---

Base Period Maximum Jitter : 47000 ns

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Parallel Port Setup
=============
Outputs (PC to Mill): Invert
Pin 1: ESTEOP OUT NO
Pin 2: X Step YES
Pin 3: X Direction NO
Pin 4: Y Step YES
Pin 5: Y Direction YES
Pin 6: Z Step YES
Pin 7: Z Direction YES
Pin 8: A Step YES
Pin 9: A Direction YES
Pin 14: Unused
Pin 16: Unused
Pin 17: Unused

Input (Mill to PC): Invert
Pin 10: Unused
Pin 11: Unused
Pin 12: Unused
Pin 13: Unused
Pin 15: Unused

Parport Base Address: 0

Output pinout presets: Sherline (default)

=============
Axis Configuration - X and U - AXIS
=============

Motor steps per revolution: 200
Driver Microstepping : 10
Pulley teeth (Motor : Leadscrew) : 1 : 1
Leadscrew Pitch : 82 mm/rev (or is this rev/mm?)
Maximum Velocity : 127mm/s
Maximum Acceleration : 1016mm/s (or is it in s2?)

---

Home Location : 0
Table travel : 0 to 2650 (mm or is this in linuxCNC units?)
Home Switch location : 0 (default)
Home Search velocity : 0.05 (default)
Home Latch direction : same (default)

=============
Axis Configuration - Y and V - AXIS
=============

Motor steps per revolution: 200
Driver Microstepping : 4
Pulley teeth (Motor : Leadscrew) : 1 : 1
Leadscrew Pitch : 12.7 mm/rev (or is this rev/mm?)
Maximum Velocity : 127mm/s
Maximum Acceleration : 1016mm/s (or is it in s2?)

---

Home Location : 0
Table travel : -1550 to 0 (mm or is this in linuxCNC units?)
Home Switch location : 0 (default)
Home Search velocity : 0.05 (default)
Home Latch direction : same (default)

=================================

here is the issue:

1. while running "TEST THIS AXIS" on X-axis
Velocity : 25mm/s
Acceleration : 1016mm/s
Test Area : +/- 10mm

X axis seems to go slightly more than the intended 5mm from mid point (covering a total of 10mm distance), hence when I hit RUN again to stop, it doesn't return to the starting point, it will be short of a few mm.

using the same values on V axis, it will go about the same distance, and after a few continuous runs, it will start to move further away from the starting point. and so when I hit the RUN button to stop it, it will stop no where near the starting point.

for Y and U, amazingly it is quite precise, as after I test to run 100mm, it is quite accurate.

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issue

2. so i tried with these settings and run on linuxCNC, with the edited HAL and INI files to setup U and V in HAL as well as for the 9 axis in INI.

I also corrected in HAL the axis for U and V, changing 2 to 6 for U and 3 to 7 for V.
in the INI file, I simply copy the information from X and paste it for axis 2, 3, 4, 5, 8.

in linuxCNC, i ran G1 F5000 X100, and it went off the chart, with way more distance, and when I do G1 F5000 X0, it will over shot the 0 point in distance.

However, in linuxCNC, it indicates that my X has indeed travel 100mm and back to 0 again, quite different from the actual physical distance traveled.

the same can be said for my V axis, it will go almost 100mm but it will not return to 0 point. It will be a few mm short of 0mm.

again, Y and U axis are fine and the motors also sound smooth and normal to me.
X and V motors are more aggressive in terms of their sound and movement speed.

=================================

I hope this can shed some good light into what has happened and how confused and somewhat frustrated I am, as I am depending now on this to finish up my work.

hopefully kind soul here sees this and is willing to help me get on with my linuxCNC.

thanks again,

if there's any questions, please ask me right away, cause i really need to get this done and fixed.

List your hardware, how are motors mounted and to what, what drives, anything and everything, pictures would help.
I understood the part with 12.7mm pitch screws, but why is the "82mm" on some axis and on others 12.7, lower the acceleration to 100 and test with that.
Do a test with velocity at 10 and acceleration 100, see if that is ok, then you can test with higher values.

Looking at the last INI file posted, the SCALE parameter for the V axis is completely different to all the others.

Just edit that by hand. Stepconf might be trying to scale for degrees not mm.

In fact, just accept that Stepconf is now finished with. You should now deal directly with the INI and HAL files.

Hi Tommy,
thanks for helping out.

yes, on the X and U axis, its horizontal on each side, and i am using rack and pinion styled, so its about 82mm travel per 1 revolution.

and on the Y and V axis, its vertical on each side, I use a 5start ACME leadscrew for that.

the motors are direct drive, mounted on aluminum plates, then with a coupler to connect the two.

I have used this machine for over a year without any problems. and yes I did test with only 20mm/s, and also lower accel at about 50mm/s. while its slow, the difference in distance is still apparent.

what I don't really understand is that, how come only one axis of the horizontal and vertical is affected, while the other is working just fine with the same settings?

thanks

thanks for the quick help Andy

I will look into that and thanks for also pointing it out.

by the way, how do I see if its scale for degrees or distance (mm)?