Adding probe offsets to SCREW_TILT_CALCULATE command

General Discussion
1

Hi, i was just wondering why the SCREW_TILT_CALCULATE command and its configuration don’t account for probe offsets? I know it doesn’t bother many people or tends to be an issue, but it seems like a weird inconsistency compared to other probe using commands like BED_MESH_CALIBRATE and PROBE_CALIBRATE.

That’s all. :3

2

I’m not sure that I understand the question.

The screws_tilt_adjust config section requires you to enter the screw1: coordinates so that your probe’s tip is ideally directly over the screw’s center. Repeating this for every screw involved.

What effect should the offset have?

3

my thought process was revolving around having to add the probe offsets to the screw positions, which while easy doesnt always work out exactly. its just an annoyance i have with klipper. it would be easier to just put in the actual coordinates of each screw and have klipper include the probe offsets itself.
this would also mitigate having to change and recalc the screw coordinates with every probe/build volume based config change.

edit: wanted to add, im basically asking “why are the probe offsets handled by klipper for everything except screw_tilt_calculate?” it seems like an oversight thats easily fixed. ease of use fixes etc

4

I still do not understand what the benefit of it would be. The offset is simply not needed for this kind of operation, and there is practically no way to add the screw coordinates directly. Even if you had a full-fledged and exact 3D model of the entire printer, you would still need the coordinates in the printer’s own coordinate system, i.e., the coordinates of the toolhead under which the probe’s tip is over the screw.

The typical workflow is:

  1. Jog the printer head around until the probe’s tip is directly above the screw’s center.
  2. Issue GET_POSITION.
  3. Note the coordinates of the printer head.
  4. Enter the coordinates in the config.
  5. Repeat for every relevant screw.

Because it has absolutely no meaning for this process. The offsets are needed for operations where a sample is taken with the probe’s coordinates but the actual compensation is done under nozzle coordinates, e.g., bed mesh compensation.

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5

ill put it this way: why does each screw inside [screws_tilt_adjust] need the probe offset baked in, while nothing else does? bedmesh min and max dont need it baked in. probe calibrate command does the offset by itself. its inconsistent and seems like an oversight. sure its not a functional issue but why not get that in line with everything else inside the configs.

if you still dont understand what im talking about, i dont know what will lmao.

6

As stated above:

1. Jog the printer head around until the probe’s tip is directly above the screw’s center.
2. Issue GET_POSITION

So, it just does not matter. It is done that way because it simply works.

About consistency with other modules, this is also pretty simple, they were written by different people at different times, that is it.

Hope that helps.

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