Meshmap / deltamap looks really wrong

Stoop

is this really really wrong?

How do I fix it?

EasyTarget

It would help if you could confirm what type of printer; I assume it is a delta? IIRC you are using a BLtouch? And maybe describe the bed; is it glass? How flat is it anyway? Do you have level adjusters on it? Putting a problem in context gets faster and more accurate replies.

Make sure you have delta calibration nailed down first (eg; probe calibration etc).
https://duet3d.com/wiki/Calibrating_a_delta_printer
This looks like the fundamental calibration is wrong. (but it could be other things.. context.)

If your bed is tilted (looks tilted in these images) I'd suggest 8-factor compensation for the final G30 command in [c]bed.g[/c], this adjusts the X and Y tilt angles as well as height and tower positions. I use it with 10-point probeing (6 outer, 3 inner, centre) on my delta with a glass bed that is slightly tilted, and am very satisfied with the results.

PS: Do Not Home after calibrating.. endstop jitter can throw the mesh off. Home, calibrate, generate mesh all in one go (nozzles and bed hot). Then when printing; heat, home, calibrate, print (or have the home command in your start gcode with a calibration command afterwards).

Stoop

Delta printer, Boots Industries BIv25.
glass is round, at the 3 mounts, I leveled the bed against a zero'd extruder to .01mm
Z probe is a piezo inside a mechanical probe. probe gets pulled out by magnet and pushed in by a retractor.

Bed has a 1mm "dip" or curve towards the center (slightly concaved) from the edges.

But I just did a 10mm print and its pretty close. I was very concerned that the extruder was going to try to drive into the bed at the edges.