# Y Positioning of Probe during G29 is not as expected
**URL:** https://marlin.crc.id.au/forum/t/y-positioning-of-probe-during-g29-is-not-as-expected/2016
**Category:** Support
**Created:** [7 January 2024 10:40 UTC](https://marlin.crc.id.au/forum/t/y-positioning-of-probe-during-g29-is-not-as-expected/2016 "2024-01-07T10:40:11Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@niederschelden](https://marlin.crc.id.au/forum/u/niederschelden)
#### Post date: [7 January 2024 10:40 UTC](https://marlin.crc.id.au/forum/t/y-positioning-of-probe-during-g29-is-not-as-expected/2016/1 "2024-01-07T10:40:11Z")
I am an experienced 3D printer user but have recently built my first printer from scratch. The printer is working as expected, but I am facing difficulties with Auto Bed Leveling.
The relevant adjustments I made in the “configuration.h” file are as follows:
#define EXTRUDERS 2
//#define HOTEND\_OFFSET\_X { 0.0, 38.00 } // (mm) relative X-offset for each nozzle // Currently commented out, as I set the offset in CURA
#define FIX\_MOUNTED\_PROBE // Inductive probe
#define NOZZLE\_TO\_PROBE\_OFFSET { 17.25, -36, -0.1 } // Relative to E0
#define AUTO\_BED\_LEVELING\_BILINEAR
#define RESTORE\_LEVELING\_AFTER\_G28
#define EXTRAPOLATE\_BEYOND\_GRID
#define X\_BED\_SIZE 210 // Actual 235, but limited to 210mm for E0
#define Y\_BED\_SIZE 170 // Actual 190, issues with auto bed level sensor extending beyond the bed in Y
#define X\_MIN\_POS -38 // The endstop is positioned so that E1 is at X0 when E0 is at the Endstop, hence E0 must have its X0 at endstop+38
#define PROBING\_MARGIN 0 // Does not function, hence more precisely defined in “configuration\_adv.h”
in adv:
#if PROBE\_SELECTED && !IS\_KINEMATIC
#define PROBING\_MARGIN\_LEFT 5
#define PROBING\_MARGIN\_RIGHT 0
#define PROBING\_MARGIN\_FRONT 40 // It should no longer extend beyond the bed, but it does
#define PROBING\_MARGIN\_BACK 0
#endif
In reality, the first probing point starts at about X5 and Y100 instead of Y0, as hoped. To make probing work, I temporarily reduced the bed size by 20 mm. In case of larger ojects to print, I plan to release more bed using M428. However, I am uncertain how Marlin will calculate Z-correction if the bed size was different during the probing process. I would appreciate any coment that helps me to force marlin to start on the Y0 line with its probing.
Thank you very much
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### Author:  [@system](https://marlin.crc.id.au/forum/u/system)
#### Post date: [22 January 2024 21:15 UTC](https://marlin.crc.id.au/forum/t/y-positioning-of-probe-during-g29-is-not-as-expected/2016/3 "2024-01-22T21:15:34Z")
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