Strange: after y-axis homing x position gets new x-value

Hi All,

I have the Ormerod 2 running now for a week, and I have not yet finished all the testing and tweaking. While I was tweaking the homey.g, homex.g, homez.g and homeall.g files I noticed that there is something unexplainable happening. When I do a y-axis homing (either through web interface or Ponterface), the x-position reading is shifting 11,34mm each time I do a y-axis homing. The real position of the extruder in not shifting in the x-axis (only the x-position reading). I have altered the homey.g file to this (also added some comments in order to understand what is happening):

G91 ; set movements relative
G1 Z5 F200 ; move upwards 5mm at 200 mm/min to make sure we don't hit anything
G90 ; set movements absolute
G1 Y-250 F2000 S1 ; move to y=-250 (to be sure to hit y=0?) at speed 2000mm/min untill hit end-stop(S1)
G92 Y0 ; define this position as y=0mm (the home position)
G1 Y3 F200 ; move to y=3mm with speed 200mm/min
G1 Y-30 F200 S1 ; move to y=-30mm with speed 200mm/min untill hit end-stop(S1)
G92 Y0 ; re-define this position as y=0mm (the home position)
G1 Y5 F500 ; adjust the Y value to put the nozzle on the edge of the bed
G92 Y0 ; re-define this position (edge of print bed) as x=0mm (the home position)
G91 ; set movements relative
G1 Z-5 F200 ; move downward 5mm at 200 mm/min
G90 ; set movements absolute

NOTE: I added all my homing files as attachment (they all contain comments about the meaning of each instruction).

When I do all these g-code instruction seperatly, I get what I expect, but when I press the y-axis homing button it yields this strange behaviour. What did I overlook? Any explaination?

Thanks,

M1k3l

This is a known problem with RRP's official firmware when you are using axis compensation. I fixed it in my fork several months ago. You may also find that the X and Y positions shift every time you home Z.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi All,

I was wrong saying the individual g-code instructions from homey.g file did not give this same error. IT DOES ALSO HAPPEN WITH THE INDIVIDUAL G-CODE INSTRUCTIONS!

New observation:
Everytime the instruction: "G1 Y-250 F2000 S1" (or any negative Y that is going to hit the endstop) then the x-position is altered (each time approximatly with 7,5mm; actualy firs time 7,50mm, second: 11.35mm, third: 18.86mm)

Why is the x-position altered when I do an y-axis homing? The physical position of the extruder head remains unchanged but somehow the value of the x-position is changed!!!

Thanks,

M1k3l

INSTRUCTIONS FROM PROMT:

>>>M114
SENDING:M114
X:0.002628 Y:0.003846 Z:1.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G91
SENDING:G91
>>>G1 Z5 F200
SENDING:G1 Z5 F200
>>>M114
SENDING:M114
X:0.002628 Y:0.003846 Z:1.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>M114
SENDING:M114
X:0.003958 Y:0.000217 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G90
SENDING:G90
>>>G1 Y-250 F2000 S1
SENDING:G1 Y-250 F2000 S1
>>>M114
SENDING:M114
X:7.509664 Y:200.025360 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>M114
SENDING:M114
X:7.509664 Y:200.025360 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G92 Y0
SENDING:G92 Y0
>>>M114
SENDING:M114
X:7.509664 Y:0.000000 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G1 Y3 F200
SENDING:G1 Y3 F200
>>>M114
SENDING:M114
X:7.517664 Y:2.994879 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G1 Y-30 F200 S1
SENDING:G1 Y-30 F200 S1
>>>M114
SENDING:M114
X:11.350146 Y:200.025360 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>M114
SENDING:M114
X:11.350146 Y:200.025360 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G92 Y0
SENDING:G92 Y0
>>>M114
SENDING:M114
X:11.350146 Y:0.000000 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G1 Y5 F500
SENDING:G1 Y5 F500
>>>M114
SENDING:M114
X:11.357195 Y:4.995131 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G92 Y0
SENDING:G92 Y0
>>>M114
SENDING:M114
X:11.357195 Y:0.000000 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000
>>>G1 Y-250 F2000 S1
SENDING:G1 Y-250 F2000 S1
>>>M114
SENDING:M114
X:18.859663 Y:200.025360 Z:6.000000 E0:0.000000 E1:0.000000 E2:0.000000 E3:0.000000 E4:0.000000

Hi DC42,

SO remedy is taking your fork, or is there another solution? Can I use it with all the standard Ormerod 2 stuff (without the balanced Z-probe you developed)?

Are there specific considerations/settings I have to do? Do you have a manual/instructions online how to install your fork?

Thanks,

M1K3L

Another solution is to set up your machine very accurately so that you don't need to use axis compensation.

To use my fork you can keep your config.g and homing files but you need to use my web interface files. There is a line to add to the config.g file to tell the firmware where the Y endstop is. See [forums.reprap.org] for details.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I highly recommend either dc or zombiepantslol's firmware forks. Tons of additional useful features, bugfixes and other which seem to take RRP foreever to correct/add.
Plus, frankly the web interface alone is worth the effort of loading it.