Z axis problem

After I have made several prints, I run into a strange issue now.
Just changed config.g and made setbed.g according to alignment instrucions.

My config.g
; RepRapPro Ormerod
; Standard configuration G Codes
M111 S1; Debug on
M550 POrmerod; Set the machine's name
M551 Preprap; Set the password
M552 P192.168.1.15; Set the IP address
M553 P255.255.255.0; Set netmask
M554 P192.168.1.1; Set the gateway
M555 P2; Emulate Marlin USB output
M92 E420; Set extruder steps/mm
G21 ; Work in mm
G90 ; Absolute positioning
M83 ; Extrusions relative
M558 P1 ; Turn Z Probe on
G31 Z1.9 P700 ; Set Z probe height and threshold
M906 X800 Y800 Z800 E800 ; Motor currents (mA)
T0 ; Select extruder 0

; setbed.g RepRap Ormerod platform calibration and xyz correction
G1 Z10 ; 10mm up
G28 X0 Y0 ; home the X and Y axes
G1 X60 Y0 ; go to foil
M557 P0 X60 Y0 ;
M557 P1 X60 Y170
M557 P2 X230 Y170
M557 P3 X230 Y0
G32 ; execute bed plane measurement procedure
M556 S78 X-0.8 Y0.7 Z0.8

Actions (doen't matter through web interface or Pronterface):
- I home X and Y
- Warm up the bed to 50C
- Go to alu foil G1 X60 Y0
- Put down the Z-axis until the print head touches a piece of paper
- Enter G92 Z0
- Run setbed.g

It reported always Z0.0, but now the Z value reports different values each time i do this again.
It was 0.6 now it is 25.4. I cannot print anymore, because Z axis alignment fails.
It looks as if z-axis movements are not measured correct any longer
Or the XYZ compensation does not work correct in combination with bed corrections.

I dont know what is wrong a reset does not help.

---

Kees

Ormerod #460 Netherlands

Has the lighting changed? The Z sensor is very sensitive to ambient light (both sunlight and incandescent light) unless you change some component values.

---

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].

PS - another thing that can cause your G31 readings to change at a given nozzle height is if the hot end is sagging. This happened to me after a few prints, and I had to reposition and tighten up the screws holding the hot end to the nozzle mount. I suggest you re-do your G31 calibration, and see whether the value is significantly different from the value you have entered in config.g.

Edited 1 time(s). Last edit at 01/03/2014 10:55AM by dc42.

---

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 have a constant light, did not change it.
Searched again the forum and saw something about the home instruction in setbed.g.
I don't think the hot end is sagging.
Every time I run setbed.g the situation gets worse. I starts with about 0.6mm and errors become greater higher every time it runs.
Can the M556 be repeated or does it correct on new bed compensation values?
Is automatic bed compensation affected by M556?
Then the M556 should not be in setbed.g (like the instructions tell) but in config.g or a seperate xyz compsation.g file

Edited 1 time(s). Last edit at 01/03/2014 11:14AM by gampie.

Hi,

I'm fairly certain that your problem is with the G32 command for auto bed compensation. I had similar issues with using G32 - I think it's buggy send my hot end crashing into the bed !!!
Remove G32 from you setbed.g file and add G30 manual settings.
Example from RepRapPro:

G30 P0 X60 Y20 Z0.0

G30 P1 X60 Y180 Z-0.3

G30 P2 X180 Y180 Z0.2

G30 P3 X180 Y20 Z-0.5 S

Insert your own Z readings as per the instructions.

HTH,

Simon

---

RS Ormerod No 192

I can only second Simon. Never used automatic bed leveling nor proximity sensor.
Printing for about two weeks now w/o (big) problems. But all manually.
I think the whole web-stuff, proximity thing and leveling is very beta.

Just my 2c.

Markus

---

XBee & electronics blog: [lookmanowire.blogspot.com]

1. I think you are supposed to run the bed compensation with all the M556 values zero, then do an M556 to set the values for your machine - as you are doing.

2. I get much better results using white PVC tape instead of alu tape on the bed corners. Ian says that white paper works too.

3. Have you re-measured your G31/nozzle height value, as I suggested already?

4. I always start the G32 with the nozzle a few mm above the bed, although I don't know whether that matters, it depends on whether the G32 code lifts the nozzle enough at the start.

---

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].