Z Homing - not working? Omerod 1

Hi Folks,

I have what seems to be a newbie question that I can't seem to figure out with my Omerod 1. I've followed the instructions in 'Commissioning' to set the ZProbe height, which seems to be close to normal parameters (G31 Z4.20 P600 ) which I have added to the Config.g file, and deleted the original G31 command. After transferring this to the SD Card, and then try to Home Z, the z axis goes up 5mm, then seems to go down about 3.5mm, then does nothing. It doesn't seem to matter where the Z height is. It's as if the G31 and/or the IR sensor is being ignored completely. It also sets Z=0 wherever it ends up, even if that's 30mm above the bed. I have confirmed the SD card is being read at startup.

Does anyone have any thoughts? I'm setting this up (finally) after a very long hiatus (like 10 months).

I've copied my Config, and ZHome file contents below for reference.

Thanks!


***********************************************************
Config.g file:
; Configuration file for RepRap Ormerod 1

; RepRapPro Ltd
;
; Copy this file to config.g if you have an Ormerod 1

; If you are updating a config.g that you already have you
; may wish to go through it and this file checking what you

; want to keep from your old file.

;
; For G-code definitions, see [reprap.org]
;

M111 S0 ; Debug off

M550 PMy RepRapPro Ormerod 1 ; Machine name (can be anything you like). With DHCP enabled connect to (example) [reprapproormerod1] (machine name with no spaces).

M551 Preprap ; Machine password (currently not used)

M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address

;M552 P0.0.0.0 ; Un-comment for DHCP

M552 P192.168.0.16 ; IP address, comment for DHCP

M553 P255.255.255.0 ; Netmask

M554 P192.168.0.1 ; Gateway, comment for DHCP

M555 P2 ; Set output to look like Marlin

G21 ; Work in millimetres

G90 ; Send absolute corrdinates...

M83 ; ...but relative extruder moves

M906 X800 Y1000 Z800 E800 ; Set motor currents (mA)

M305 P0 R4700 ; Set the heated bed thermistor series resistor to 4K7

M305 P1 R4700 ; Set the hot end thermistor series resistor to 4K7

M569 P0 S1 ; Set X axis direction

M92 E420 ; Set extruder steps per mm

M558 P1 ; Use an unmodulated Z probe (change to P2 if you update to the modulated probe)

G31 Z4.20 P600 ; Set the probe height and threshold (from commissioning instructions - TM)
M556 S75 X0 Y0 Z0 ; Put your axis compensation here

M201 X500 Y500 Z15 E500 ; Accelerations (mm/s^2)

M203 X15000 Y15000 Z100 E3600 ; Maximum speeds (mm/min)

M566 X200 Y200 Z30 E20 ; Minimum speeds mm/minute

M563 P0 D0 H1 ; Define tool 0

G10 P0 S-273 R-273 ; Set tool 0 operating and standby temperatures

;M563 P1 D1 H2 ; Define tool 1 Uncomment if you have a dual colour upgrade

;G10 P1 X19 S-273 R-273 ; Set tool 1 operating and standby temperatures Uncomment if you have a dual colour upgrade




**************************************************************************
ZHome GCODE:

G91 ; set movement to relative mode

G1 Z5 F200 ; move Z up 5mm

G90 ; set movement to absolute mode

G1 X0 Y0 F2000 ; move X and Y to probe point. ADJUST X and Y values to get Z probe over target.

G30 ; home Z, using values from G31 in config.g

G1 Z0 F200 ; move Z to Z=0

Edited 3 time(s). Last edit at 12/29/2015 11:44PM by parper101.

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Green Machine - slowly becoming multicoulored!

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Edited 1 time(s). Last edit at 12/29/2015 11:28PM by parper101.

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Green Machine - slowly becoming multicoulored!

Why do you probe at X=0 Y=0? I guess the probe will stay above the endstop piece when you home Z, so it's not surprising that you don't get a reasonable Z value. Also, be aware that the Z trigger value of the stock O1 probe changes depending on the external lighting, so I really suggest you consider to upgrade to dc42's IR probe.

Try to change G1 X0 Y0 F2000 to G1 X45 Y0 F2000, that's what RRP's default homing files use.

Hi Chrishamm,
The probe works exactly as the commissioning steps say it should, so I can assume it's working fine. I have previously changed my X0, Y0 to have the IR sensor directly above the center of the paper. That's why i'm homing at "X=0, Y=0".

Hi All,
Unfortunately this doesn't answer my question however as I've now changed it back to a more stock X=0, Y=0 as suggested and have the same results, (up 5, down 3.5 ish) when homing z, no matter where 'z' is at the time. i.e. it could be at z=0 (manually placed) or z=100 (manually placed) the 'home z' performs the same action.

Am I supposed to put the 4.2mm movement set by G31 in my config file into the line: G31 Z4.20 P600... that is the last line of my ZHome (maybe) should read: G1 Z-4.2 F200 (instead of G1 Z0 F200)?


Thanks very much in advance.

Edited 1 time(s). Last edit at 12/30/2015 05:52PM by parper101.

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Green Machine - slowly becoming multicoulored!

Hi Folks,

Is this a hopeless issue ... nobody has had it before.. its still not resolved and zeroing z by hand is annoying. any thoughts would be appreciated

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Green Machine - slowly becoming multicoulored!

I strongly suspect that your Z probe is not working properly. You may have a bad connection at one end of the blue wire. Or perhaps you upgraded the firmware and didn't move the blue wire to the correct pin on the expansion connector.

So I suggest you test the Z probe again. It's easier if you use the web interface, because it provides a continuous readout of the Z probe reading.

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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].

Thanks DC42, i will try this in the morning.
Much appreciated.

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Green Machine - slowly becoming multicoulored!

Ok, so i've tested all of the connection wires and they all seem fine.

The ZProbe in the web interface however, is very erratic..
It seems to be reporting some wild values every third report or so for the first set of numbers, not the ones in brackets (like from 102 101, 104, 134217726, 101, 102, 134217726). The number following in brackets seems relatively constant.

Is there anything I can do to fix this or do i have to order another one? I can't find a ZProbe on the website, and though I REALLY like DC42's I haven't got the $ for such an upgrade.
It's now affecting my xhome, as (i think) when it errors it thinks it's hit the ledge attached to the z mount.

Frustrated.
Thanks for any help in advance.

ALSO: I've noticed my y axis has suddenly (today) decided to 'pause' every once in a while, throwing my prints off.. could these two be related in some way?

Edited 1 time(s). Last edit at 01/03/2016 10:24PM by parper101.

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Green Machine - slowly becoming multicoulored!

Which firmware version are you using? I remember fixing a similar issue in my fork several versions ago.

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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].

The Y axis problem will not be related to your Z homing issue. There are 3 usual causes:

1) The belt is too loose and sometimes slips a tooth.
2) The grub screw in the motor pulley is not tight or is not situated exactly over the flat of the shaft and so the pulley is slipping on the motor shaft.
3) A part of the print has a blob or has lifted and is catching on the nozzle, causing the motor to skip a step (you can try increasing the motor current to 1000mA to prevent that happening).

Dave