Bug in Marlin autoleveling?

I have a folger2020. The z motors are mounted on the top, not the bottom.

This doesn't seem to be accounted for with autoleveling. I'm guessing perhaps the autoleveling code has the z motor moves hardcoded rather than mulitplying by -1 as needed.

When I autolevel, both for 3 point and linear, all that happens is the z axis moves up. Never moves down. I manually trigger the probe with my finger, and it moves to the next point, but only up on the z axis.

Again, when autoleveling, the z axis moves never decrease, not even once.

I can provide a video of this behavior if necessary.

Also: moves with G1 work fine and M114 reports correct z position.

Edited 2 time(s). Last edit at 08/10/2018 08:53PM by foul_owl.

I've seen some weird behavior in Z axis moves with Marlin,depending on the acceleration values.

My newer printer had the acceleration on the Z axis set really low for it factory settings, and it would sometimes simply not move. In that case it was small moves (Like layer changes) would simply not happen. Increasing the acceleration fixed that. I also had a case where it wouldn't do SLOW moves (Like probing) but the lifting would be okay. I had results very much like what you're describing.

For your configuration, look at the Z maximum movement speed, and the Z acceleration values, also look at the probe speed.

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MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Thank you! Let me try that.

Ok, I tried increasing the max feedrate for z from 2 to 4 (matching my old other printer, which had working autoleveling), no luck.

I tried increasing the max acceleration for z to 50, matching my old printer again, still no luck.

I then tried changing the homing feedrate to (3*60) matching my old printer, *still* no luck. It moves faster for sure, but it's not moving down.

I couldn't find a setting for max z movement speed.

I think there is a bug here and I'm dead in the water until it's fixed. This is extremely frustrating.

Created:
[github.com]

Thank you for helping me here.

Try bumping up the Z acceleration again. (I bumped mine to 2500 as a "stupid high" value just to see if it would work. It didn't actually seem to do any harm, and it worked, so I left it there. (Pretty sure that X and Y are still at 5000.)

---

MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Tried 2500. Unfortunately still doesn't work.

I wonder if there is something just misconfigured about my Configuration.h, something autoleveling related that I'm just not seeing:
[gist.github.com]

(bugfix 2 branch version)

Edited 1 time(s). Last edit at 08/14/2018 06:24PM by foul_owl.

Why not upload your configuration.h file so we can take a peek?

It's there! It's in the gist linked in my last post thank you!

Here's the updated one also, with the new accleration, etc, created from the zip download version of Marlin:
[gist.github.com]

Edited 1 time(s). Last edit at 08/14/2018 06:41PM by foul_owl.

Aaaaand my github account was flagged. Again.

I'll just attach here.

Let's see..

Line 145

#define DEFAULT_NOMINAL_FILAMENT_DIA 3.0

Probably won't cause a problem unless you use volumetric extrusion, but most slicers don't. (Unless you're actually using 3mm filament. does anyone anymore?)

Line 608

#define DEFAULT_MAX_FEEDRATE          { 250, 250, 4, 22 } // change z back to 2

4 seems awfully low. Mine is set to 20, but that's also at 400 steps/mm, as opposed to your 3840, so it SHOULD be able to move a lot faster. I think I had it set to 10 on my I3 (4000 steps/mm)

Side note: Assuming a 200 steps/rotation motor and 16X microstepping, a 1.2mm lead screw is kind of unusual. M5 threads have a standard lead of 0.8mm, M6 thread has a standard lead of 1.0mm, and M7/M8 thread has a standard lead of 1.25mm.

Line 788

//#define MULTIPLE_PROBING 2

I have this uncommented. I wanted the fast/slow probe. The fast/slow feed rates are defined based on the homing rate definied at 1143 (3mm/s looks like) Might be worth tryng to see if it moves. (Also, if it probes once, then not the second at half speed)

Line 967

#define AUTO_BED_LEVELING_LINEAR

Line 1010

#if ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR)

  // Set the number of grid points per dimension.
  #define GRID_MAX_POINTS_X 3
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  // Set the boundaries for probing (where the probe can reach).
  //#define LEFT_PROBE_BED_POSITION MIN_PROBE_EDGE
  //#define RIGHT_PROBE_BED_POSITION (X_BED_SIZE - MIN_PROBE_EDGE)
  //#define FRONT_PROBE_BED_POSITION MIN_PROBE_EDGE
  //#define BACK_PROBE_BED_POSITION (Y_BED_SIZE - MIN_PROBE_EDGE)

  // Probe along the Y axis, advancing X after each column
  //#define PROBE_Y_FIRST

  #if ENABLED(AUTO_BED_LEVELING_BILINEAR)

    // Beyond the probed grid, continue the implied tilt?
    // Default is to maintain the height of the nearest edge.
    //#define EXTRAPOLATE_BEYOND_GRID

    //
    // Experimental Subdivision of the grid by Catmull-Rom method.
    // Synthesizes intermediate points to produce a more detailed mesh.
    //
    //#define ABL_BILINEAR_SUBDIVISION
    #if ENABLED(ABL_BILINEAR_SUBDIVISION)
      // Number of subdivisions between probe points
      #define BILINEAR_SUBDIVISIONS 3
    #endif

  #endif

You define linear probing, but do not define the left/right/front/back edges. I would probably uncomment these.

Personally, I'm using 3 point levelling on mine, because the probe setup needs specialized locations on the bed, and my kit came that way.

---

MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts

Ok...I didn't have the zmax pin enabled (USE_ZMAX_PLUG) so it was basically thinking the probe pin was triggered at all times...I feel very stupid but at least progress is getting made

Thank you for your help!!