AutoBim

AutoBim is a simple bed tramming utility for OctoPrint using ABL. Tramming is the process of making sure your bed is as parallel to your printer's X axis as possible. Or, put simply:

Tilted Bed + Tramming = Parallel Bed

How does it work

The plugin adds a single button to OctoPrint's navbar, because that's all it needs. When the button is clicked, a combination of GCodes G0, G28, G30, M117 and a bit of message parsing is used to create something like this (link to YouTube). Jump to 3:10 if it didn't already.

Alternatives

This functionality seems to be part of bugfix-2.0.x branch at the time of writing, i.e. see here

So you may want to check out that before using this plugin.

Why should I use it?

Doesn't Marlin already account for a tilted bed if I have an ABL probe?

Yes, but it really shouldn't. Imho ABL should be used for correcting irregularities in bed surface (warps, bumps, etc.) and for having the same distance to the bed on every print (think different beds, different bed temps, etc.). Tilted beds should be dealt with in hardware, not in software.

Couldn't I just use a piece of paper for levelling as I did before getting an ABL probe?

Sure, but where is the fun in that?

I use insert any other method here. Is this more accurate than my method?

I think that depends on the method, and even more on how good you are at your method. It may, it may not.

Requirements

• OctoPrint (duh)
• ABL probe, such as BLTouch
• Marlin firmware with support for
  • G30 - Single Z-Probe
    • Send G30 X30 Y30 over OctoPrints Terminal. Make sure to home the printer before you do.
  • M117 - Set LCD Message
    • Send M117 Hello World over OctoPrints Terminal and look for Hello World on the printer's screen
• Klipper firmware with:
  • Macros to support:
    • G30 command (probe a location)
    • G29 D / G29 J commands (clear bed mesh)
    • Examples are provided in Klipper Macro Examples
  • Ability to display a message with the M117 command
    • Test as per Marlin

Setup

Install via the bundled Plugin Manager or manually using this URL:

https://github.com/j-be/AutoBim/archive/master.zip

Hint: Keep your hands away from the printer whenever possible. This not only reduces the risk of your hand colliding with the knob (and thus putting it out of level again) because the printer suddenly moves. It also seems to increase measurement accuracy, at least of my BL Touch. So: wait, adjust, hands off, wait, adjust, hands off, ...

Preparation

Check XY Probe Offset

Marlin needs to know where your probe is relative to the nozzle. This position is known as XYZ Probe Offset. While pretty much everybody will have Z offset calibrated, X and Y are sometimes neglected. They shouldn't though, they are important, too.

To check, send the following commands to the printer (e.g. via OctoPrint's Terminal) or do it any other way you are comfortable doing it:

1. G28; Home the printer
2. G0 Z20; Move the nozzle up so it is a safe distance from the bed. I consider 20mm to be safe, feel free to use a different value.
3. G0 X30 Y30; Probe X=30, Y=30
4. Mark the exact spot below the nozzle. This can e.g. be done be putting a piece of paper on the bed and marking the spot there. If you have a glass bed and a marker you know you can remove without residue, use that. Feel free to lower the nozzle a little bit if that makes it easier.
5. G30 X30 Y30; Probe the point. The printer should now move the probe to the point we marked in the step above.

If it probed the point your printer is correctly set up. If not, check out M851 in Marlin documentation for further information on the topic.

If you are using Klipper this is setup and configured as part of Probe Calibration in the Klipper documentation.

Configuration

Defaults are for an Ender 3 sized printer and a BLTouch. You can configure:

• Invert arrows on display, e.g. for inverse screw threads on the adjustment screws
  • Default: Off
• Enable/Disable multi-pass (i.e. go on until a full round measures ok)
  • Default: On
• Accuracy threshold
  • Default: 0.01
• Unified Bed Leveling - Enable this if your firmware was compiled with UBL
  • Default: False
• Delay between corners - Wait the given amount of seconds before moving to next corner
  • Default: 0.0
• Points to probe
  • Default: (30, 30), (200, 30), (200, 200), (30, 200) (Ender 3)
  • Note: These coordinates refer to probe position, while most other coordinates (e.g. what is displayed on screen) refer to nozzle position. Try to use the points exactly above the set screws if that is possible (see Works fine on the first corner, display says ok. moving to next but nothing happens below) or get as close as possible.
• Show button in Navbar
  • Default: True
• G30 command (probe) custom pattern
  • Default: Blank (use default for supported firmware)

Planned are (ordered by assumed priority):

• Allow for a different amount of probe points

Klipper Macro Examples

A set of macros to add support for G29 and G30 are required for this plugin to work with Klipper. Examples are provided here that you can use to add the minimum functionality required.

G29.cfg

[gcode_macro G29]
gcode:
  {% if 'D' in params or 'J' in params %}
    BED_MESH_CLEAR
  {% else %}
    { action_respond_info("Functionality not implemented. D and J commands to clear bed mesh are supported.") }
  {% endif %}

This macro runs the command to clear the bed mesh if either G29 D or G29 J are run. It doesn't provide any of the other G29 functionality from Marlin, we just need the bed mesh clear functionality for this plugin.

G30.cfg

[gcode_macro G30]
gcode:
  {% set x = params.X | default(0) | float %}
  {% set y = params.Y | default(0) | float %}

  {% set x_offset = 0 | float %}
  {% set y_offset = 0 | float %}

  {% if printer.configfile.config.bltouch.x_offset is defined and printer.configfile.config.bltouch.y_offset is defined %}
    {% set x_offset = printer.configfile.config.bltouch.x_offset | float %}
    {% set y_offset = printer.configfile.config.bltouch.y_offset | float %}
  {% elif printer.configfile.config.probe.x_offset is defined and printer.configfile.config.probe.y_offset is defined %}
    {% set x_offset = printer.configfile.config.probe.x_offset | float %}
    {% set y_offset = printer.configfile.config.probe.y_offset | float %}
  {% endif %}

  {% set y = y - y_offset | float %}
  {% set x = x - x_offset | float %}

  {% if printer.toolhead.homed_axes != "xyz" %}
    { action_respond_info("XYZ must be homed first.") }
  {% else %}
    SAVE_GCODE_STATE NAME=G30_state
    G90
    {% set old_z = printer.toolhead.position.z %}
    {% if 'X' in params and 'Y' in params %}
      G1 X{x} Y{y} F4000
    {% endif %}
    PROBE
    {% if old_z is defined %}
      G1 Z{old_z}
    {% endif %}
    RESTORE_GCODE_STATE NAME=G30_state MOVE=0
  {% endif %}

Please note that this macro DOES take into account the probe offset. Probe points may still require adjusting if the offset position exceeds max travel. Your printer configuration requires either bltouch or probe to declared, with x_offset and y_offset to be both set.

This macro will:

• If provided, move to the new X and Y locations
• Probe the location
• Move back to the original Z location before the probe

It is important that your macro ensures the toolhead is a safe distance away from the bed again after probing, as X/Y travelling will occur after probing.

What is supposed to happen

Since there are quite some unknowns in the process, here a list of what should happen when you click the button in the navbar:

Step		You	Message on Display
1	Home		wait...
2	Raise to Z=20		wait...
3	Go to corner point and probe		wait...
4	Display difference and direction to rotate the knob	Turn the leveling wheel/knob/lever	e.g. 0.16 >>> (adjust) for 0.16mm to high, turn right (i.e. counter-clockwise) to correct
5	Printer goes on probing until the difference is within threshold	Turn the leveling wheel/knob/lever	e.g. -0.01 <<< (adjust) for 0.01mm to low, turn left (i.e. clockwise) to correct
6	Measurement is within threshold		ok. moving to next
6.5	If "Delay before moving to next corner" is set, wait for that amount		ok. moving to next
7	If full round completed without a difference, we are done		done.
	Else, go to Step 3 for the next corner		ok. moving to next

If that is not what happens look at Troubleshooting below. If that doesn't help consider opening an issue detailing where it goes wrong, how, and (if you have a suspicion) why.

Troubleshooting

Works fine on the first (or first and second corner), display says ok. moving to next but nothing happens

Most likely that means the printer cannot reach the point set in Points to probe because it would need move beyond what it considers to be its moving range. This is a feature known as "software endstops" in Marlin.

For your X axis, the most likely issue is X_MAX_POS set in the firmware. For most builds this will default to X_BED_SIZE, but on most printers it should be possible to raise this a little bit, e.g. on my Ender 3 Pro this can be set to 245 as it can easily move the nozzle 10mm left of the bed. It won't ever print there - that's what X_BED_SIZE is for - but moving there temporarily, e.g. for probing, is fine. The same applies to Y, i.e. on an Ender 3 Pro you can set it to 240.

Another reason could be, that PROBING_MARGIN in your firmware is set to something, that makes no sense. E.g. I heard Ender 6 stock firmware seems to set Y_BED_SIZE to 260, the bed is 290 in depth, and Creality - in there infinite wisdom - still seems to have decided to apply an additional PROBING_MARGIN of 30. This effectively makes 230 the maximum usable Y coordinate for probing.

As to why the plugin doesn't react to this condition: At least on my machine there is no indication on the log, that the printer can't do what it was told. I get an ok, which I find misleading at least. If you have an idea on how to catch this error, which doesn't involve timing the response time on a G30, feel free to open an issue for that.

I found the following sequence in OctoPrint's Terminal to work well. Assuming you'd like to find the maximum Y value:

• G28; Home the printer
• G0 Z20; Raise hotend to Z=20 to avoid collisions while moving
• G30 X30 Y195; Tell printer to probe X=30 Y=195
  • If printer doesn't move try G30 X30 Y190
  • If printer moves try G30 X30 Y192
• ... and so on, until you found the maximum Y value
• Take that value and use it as the upper Y value in Points to probe

Also, please check out if #2 sounds like a good solution to the problem, and give it a thumbs up or thumbs down respectively. Please don't comment to +1, I'd appreciate it.

As a last resort and if you have no other possibility you may consider temporarily disabling endstops in Marlin using the M121 command. Doing that could cause serious damage to your bed or printer, so once you did that always have your hand on the power switch - just in case. When you are done, be sure to reenable the endstops using M120. You have been warned!

Printer homes, moves to first corner, probes, then nothing happens. Display is stuck on wait...

This most probably means that your printer returns the measured coordinates in a format different than mine does. To check this, please go to OctoPrint's Terminal and enter a G30 (make sure you homed before and raised your hotend a little bit to avoid collisions). I'd recommend the following sequence:

1. G28; Home the printer
2. G0 Z20; Move the nozzle up so it is a safe distance from the bed. I consider 20mm to be safe, feel free to use a different value.
3. G30 X30 Y30; Probe X=30, Y=30

On my printer I see the following (irrelevant stuff and Recv: echo:busy: processing removed for brevity):

Send: G28
[...]
Recv: X:159.00 Y:122.00 Z:12.03 E:0.00 Count X:12720 Y:9760 Z:4812
Recv: ok
[...]
Send: G0 Z20
Recv: ok
[...]
Send: G30 X30 Y30
[...]
Recv: Bed X: 30.00 Y: 30.00 Z: 0.00
Recv: X:72.00 Y:35.00 Z:12.03 E:0.00 Count X:5760 Y:2800 Z:4812
Recv: ok

I am most interested in if there is a line like the Recv: Bed X: 30.00 Y: 30.00 Z: 0.00 above. If yours contains the same information, but looks different, let me know, I'm happy to add that as a setting.

I can't seem to get a full round complete - there is always one point, that is +/-0.01 off. Is something broken?

Most probably not. By using 0.01mm as threshold we are close to the BLTouch's tolerance, which means that there is already a little luck involved, too. It can take some 5, 6 rounds (and more) with only some corners off by +/-0.01 until a full run completes. If you don't care that much, you can always raise Accuracy threshold in the settings. Note, that Marlin (at least my build does this) reports only 2 decimal digits, so a setting of 0.011 will have the same effect as 0.02. At the time of writing, Marlin's presumably equivalent LEVEL_CORNERS_USE_PROBE feature uses 0.1 as tolernace by default (see here.

Additionally, keep in mind that changing one of the corners may affect other corners as well - which is why the plugin does the multi-pass in the first place. The closer your probe points are to the set screws, the less the influence. So you may want to spend a little time getting those right.

Printer does a 3-point leveling at start of tramming

This means your firmware was compiled with Unified Bed Leveling. Open the plugin settings and check the UBL (Unified Bed Leveling) checkbox.

Why is it so slow? Why doesn't the plugin read some value from the printer?

Unfortunately, all parameters referring to probing seem to be hardcoded in Marlin and are not readable via GCode. It seems, for example, the plugin is not able to override the amount the hotend is raised after probing (I think that should be LEVEL_CORNERS_Z_HOP, but I'm not even sure on that), which would be great to save some time.

Also, there seems to be no way to read stuff like TRAMMING_POINT_XY and TRAMMING_SCREW_THREAD, so I need to add them as settings.

That said: I am far from being an expert on Marlin. If you know a way to set them via G-Code, please open an issue detailing on how one can do that and I will definitely have a look at it.

Why the name?

This plugin is meant to help with bed tramming. I am from Vienna, and trams in Vienna are called "Bim" (like "bin" as in "trash bin", just with an m instead of the n).

Credits

Special thanks go to the following people:

• scottg88 for basic Klipper support
• datapaganism for adding probe offset support to Klipper macros

Credit goes to the following projects for being there and letting me look at and copy their code:

• https://github.com/jneilliii/OctoPrint-BedLevelVisualizer
• https://github.com/marian42/octoprint-preheat

Make sure to check them out, and don't forget:

"Toss a coin to your developers, o valley of plenty, o valley of plenty..."