Inconsistent behavior between "screw adjustment" and "bed mesh"

Basic Information:

Printer Model: Tronxy X3A with newly install Creatly Direct Drive Extruder
MCU / Printerboard: Bisqu SKR V1.3
Host / Raspberrt Pi 3B
klippy.log included

Describe your issue:

I recently installed a Direct Drive Extruder assembly (with BLTouch) on my ancient X3A. Elecrically and mechanically the process went very well. I plodded through nearly all of the needed recalibrations and settings in Klipper and ran many of the calibration files in Orcaslicer. So far so good, until I got to Klipper’s screw adjustment and bed mesh.

I update the probe offsets The probe is nearly in line in Y and is to the left in X, resulting in X:-42 Y:-7. I reset my X limit stop offset and Max X postion to the new values.
I then proceeded to update printer.cfg to have correct travel values for screw adjustment and bed mesh, Here’s where I ran into problems.

Bed mesh appears to locate the probe by the location of the nozzle. For example, to probe as much of the bed as I can my max position is X:190 Y:190 (with some safety). No max position limits are violated. So far so good.

I then proceeded to update the screw adjustment settings. I quickly discovered that that without violating my X-Axis max position that the probe would not go nearly as far right as is desirable (40 or so more). It appears that unlike bed mesh whcih works in terms of nozzle position, screw adjustment works in terms of probe postion. Thus, to move the probe to roughly X:190, I would have to enter X:232 in the screw adjustment section, violating my Max. X Postion. Now of course there is a solution to this, just open up Max. X position until screw adjustment works and set the X position in screw adjustment to X:232. This would work but would be horrible practice. I could run the extruder to far right by mistake and slip my belt.

Did I explain all this okay? Did I find a bug/inconsistency or am I all screwed up. Happens all the time. It is likly the code for screw adjustent and bed mesh is maintained by two different people, allowing for this sort of thing to creep in.

Thoughts?

klippy (4).log (7.5 MB)

As confusing as it seems, this is working the way it is intended, and as described in the documentation. Generally speaking, your min/max position values should be the hardware limits of your machine, meaning they should contain the entire area of motion that the machine is physically capable of. Then you would configure the slicer to ensure that during regular printing, the machine is never commanded to print outside the “bed” area. This way you can move the print head outside the print area for non-printing operations, such as print-head parking, filament changes, and bed probing.

Well, you are right, it is confusing.

Basically, you’re always commanding the toolhead to the nozzle position. You just have to remember that when what you really care about is the position of the probe, you’re still specifying the location of the nozzle.

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