# Custom firmware has improper offsets by default
**URL:** https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914
**Category:** Firmware Builder
**Created:** [18 May 2022 22:00 UTC](https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914 "2022-05-18T22:00:16Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Smiggy\_Balls](https://marlin.crc.id.au/forum/u/Smiggy_Balls)
#### Post date: [18 May 2022 22:00 UTC](https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914/1 "2022-05-18T22:00:16Z")
just attempted to build my own firmware with the firmware builder, and every time I attempt to level the bed the positioning is off of the bed, not allowing it to be leveled. With the nightly build of the 4.2.2 board with bl touch this does not happen and the offsets are at the center automatically. I attempted to set the offsets in order to probe the bed properly, but this does not work, and still goes off of the bed. what can I do to fix this? I really only need the default 4.2.2 firmware with BL touch but with linear advance ( not included in the firmware unless it’s the “advanced” version which is not in a bin file).
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### Author:  [@CRCinAU](https://marlin.crc.id.au/forum/u/CRCinAU)
#### Post date: [19 May 2022 13:39 UTC](https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914/2 "2022-05-19T13:39:33Z")
Might be able to save you a lot of time… Linear Advance doesn’t work with the v4.2.2 mainboards.
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### Author:  [@Smiggy\_Balls](https://marlin.crc.id.au/forum/u/Smiggy_Balls)
#### Post date: [20 May 2022 01:13 UTC](https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914/3 "2022-05-20T01:13:04Z")
oh ok thank you, did not know this. May have to upgrade to one of the 3rd party boards to get this feature, because I have a lot of overextrusion directly after layer starts. Is there anything I can do to mitigate this without linear advance?
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### Author:  [@CRCinAU](https://marlin.crc.id.au/forum/u/CRCinAU)
#### Post date: [21 May 2022 05:21 UTC](https://marlin.crc.id.au/forum/t/custom-firmware-has-improper-offsets-by-default/914/4 "2022-05-21T05:21:54Z")
For what its worth, the probe offsets are set by the [M851](https://marlinfw.org/docs/gcode/M851.html) command.
As for over-extrusion at the start - maybe look at retraction? Sadly, this could be so many things - including not quite set up right hardware that its very difficult to assist remotely…