true bed levelling - not bed level compensation - Does this already exist?

Dear all,

I am new to Marlin, but comfortable with programming.

I require a "Bed Leveling Calibration routine", which would function by using a Z probe, measuring 3 points on the bed, and then advising the user which screws to adjust to level the bed.

i.e the result would be a bed that is level, as opposed to compensating for an unlevel bed in software.

So far, everything I can find relates only to "Bed Leveling Compensation", with the software accounting for an unlevel or uneven print bed.

The physical build and operating environment of this printer is such that I don't expect bed levelling calibration to need to be done often.


Question: Has this already been done? Can anyone point me towards a resource on this?
If it is not already done, I am happy to implement in Marlin. Marlin is reasonably large - can anyone help point me towards where to start, e.g even just which .cpp file would be the best place to include this code?

Thankyou for your time.

If you are going to manually turn the appropriate screw to physically adjust the bed, you may be able to use the Topographical map of the grid leveling system. I introduced that almost 3 years ago:

[3dprintboard.com]

Configure your Marlin firmware to use a grid based leveling. Do a G28 followed by a G29 with a T parameter. It will show you the measured heights of the probe points.

Pick the corner that is furthest out of spec. And move it halfway back into spec.

Repeat the process several times. Your errors will get to be less and less. Pretty soon, your bed will be nearly level physically.

BUT.... You will still get better results by letting the firmware do dynamic adjustments during the print.

I've seen some people experimenting on doing that over the years.

For instance the sparkcube does it : [www.youtube.com] but I think they use Repetier firmware

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.