Auto bed leveling - so close, but one problem.

Hello all,

I've got a Prusa i3v 12" with a Rambo board. I've got the auto bed leveling servo and switch all set up, it appears to function as expected, except..

After homing X and Y, then running a G29, when it starts the probing, rather than starting in the home position, it moves to the center of the build platform, and starts probing the grid pattern from there. If I set it like the code below, it would happily crash off the end of X or Y. I tried changing these numbers to 10 and 50, just as a test, and it works, but still always starts from the center of the bed. It only probes a small section of the left front quarter of the bed.

If this is unclear, I'll get a video of what's happening. I just can't seem to figure out what is causing it to start in the center of the bed, versus the home position, which is the far back right corner of the bed.

Below this code is the output from a M501, I thought maybe there was some offset in the EEPROM, but that doesn't seem to be the case.

Any ideas?

Thanks!

    #define LEFT_PROBE_BED_POSITION 50
    #define RIGHT_PROBE_BED_POSITION 260
    #define BACK_PROBE_BED_POSITION 260
    #define FRONT_PROBE_BED_POSITION 50

    // set the max number of grid points per dimension
    // The G29 command defaults to 3 if nothing is specified.  But setting the number of probed 
    // points higher is very useful when getting a Bed Topology Report  (G29 n 5 T)
    #define AUTO_BED_LEVELING_GRID_POINTS 5

    // Uncomment one of the following four lines so the Bed Topology Report can produce a map
    // that relates accurately to your bed orientation.  

    #define ORIGIN_FRONT_LEFT
    //#define ORIGIN_BACK_LEFT
    //#define ORIGIN_FRONT_RIGHT
    //#define ORIGIN_BACK_RIGHT

SENDING:M501
echotored settings retrieved
echoteps per unit:
echo:  M92 X80.00 Y80.00 Z4000.00 E893.00
echo:Maximum feedrates (mm/s):
echo:  M203 X250.00 Y250.00 Z2.00 E22.00
echo:Maximum Acceleration (mm/s2):
echo:  M201 X1000 Y1000 Z5 E1000
echo:Acceleration: S=acceleration, T=retract acceleration
echo:  M204 S500.00 T500.00
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s),  Z=maximum Z jerk (mm/s),  E=maximum E jerk (mm/s)
echo:  M205 S0.00 T0.00 B20000 X20.00 Z0.40 E5.00
echo:Home offset (mm):
echo:  M206 X0.00 Y0.00 Z0.00
echoID settings:
echo:   M301 P22.20 I1.08 D114.00

Here's the video:

video

I did manage to solve this, but it wasn't in the way I had hoped. I believe the firmware I had downloaded wasn't set quite right for my machine, even though the bed leveling was enabled. I'm sure there's a setting somewhere that I missed that was causing my problem, but I just wasn't finding it.

I ended up downloading firmware from this repository: https://github.com/ErikZalm/Marlin

I then used winmerge to compare the firmware configuration.h from Makerfarm to the one I linked above. I copied all of the configuration variables from Makerfarm to the newly downloaded configuration.h

I also copied the thermistortables.h from the Makerfarm firmware over the one from the repository.

I used Zennmaster's auto bed leveling guides found here: http://zennmaster.com/ in combination with this guide: http://3dprintboard.com/showthread.php?9335-Rambo-Servo-Setup-for-Auto-Bed-Leveling-for-Noobs

I did some additional adjusting to the numbers for my bed size (the clips get in the way), and the range of probing.

I hope this helps saves time for anyone else interested in getting this working.

Edited 1 time(s). Last edit at 01/25/2015 06:02PM by zaa.