This guide outlines how to configure the boundaries for your bed meshes. This will help you prevent out-of-range errors and other issues like probing off the edge of the bed during meshes.
You should first complete these two guides:
Axis Limits: Find the travel/print boundaries for your machine
Probe Offsets: Calibrate your probe offsets for X,Y,Z
The mesh_min and mesh_max configuration frequently trips people up.
These values need to be PROBE coordinates, not nozzle coordinates.
However, the Klipper backend does not offset these values automatically for you.
We need to manually apply the offsets to the mesh boundaries.
The simplest way to explain this is to use an example. So I will include a snippet of example config values so we can demonstrate the math.
[stepper_x]
position_min: -5
position_endstop: -5
position_max: 250
[stepper_y]
position_min: -5
position_endstop: -5
position_max: 200
[bltouch]
x_offset: -50
y_offset: -10In this example, our mesh_min and mesh_max values would be:
[bed_mesh]
mesh_min: 0, 0
mesh_max: 199, 189Here is a diagram to help visualize the math:
In this example the probe would be mounted to the front-left of the nozzle which gives it negative offsets for both X and Y.
This is likely somewhat exaggerated from what you will see in practice, but it should help you understand the concept.
It's fairly common for the probe to be unable to reach the full range of the bed. This is especially true if you have a large probe offset.
If your probe is to the front-left of the nozzle, then the offset will affect the mesh_max values for both X and Y. Both offsets will be negative.
If your probe is to the back-right of the nozzle, then the offset will affect the mesh_min values for both X and Y. Both offsets will be positive.
If your probe is to the front-right or back-left of the nozzle, then the offset will affect the mesh_min value for one axis and the mesh_max value for the other axis. One offset will be positive and the other will be negative.
Typically the probe is mounted to the left of the nozzle. That will result in the larger offset (X) being a negative value. In my experience the Y value usually is as well, but in any case it's less of a concern due to its smaller offset.
mesh_min is simple, we can use 0,0 (the front-left corner) or bump it in a little to something like 10,10 (if we don't want to be that close to the edge)
mesh_max has to account for the range the probe can travel to. This will be less than your position_max and it's common for it to even be less than your bed size.
In my example above the probe's x_offset is -50
The stepper_x position_max is 250
That means the absolute maximum point the probe can move to is 200 (250 - 50). We use 199 (200 - 1) to be safe.
199 is the furthest point that can be used for mesh_max.x
Our probe's y_offset is -10
The stepper_y position_max is 200
That means the absolute maximum point the probe can move to is 190 (250 - 10). We use 189 (190 - 1) to be safe.
So in this example, our mesh_max has to be 199, 189 or less.
If you do not do this correctly your BED_MESH_CALIBRATE command will fail with a move-out-of-range error.
If that happens, make note of the invalid coordinates in the error message. These will provide a clue for the source of the problem.
It will likely be one of your axis moving beyond the max_position.
In that case, you'll need to revisit your mesh_max configuration for that axis and correct the error.
If the error shows a move to negative coordinates and/or the failure occurs on the left/front side of the bed, then you will need to correct your mesh_min configuration to account for the offset that was moving you beyond the physical limits.
You can use this GET_PROBE_LIMITS macro to find the physical minimum and maximum probe coordinates as well as the current probe coordinates.
This can be helpful if you'd like to avoid doing the math yourself as it will display the range of possible values that can be successfully used for mesh_min and mesh_max.
To use this macro, download the GET_PROBE_LIMITS.cfg file to your ~/printer_data/config directory and add the following near the top of your printer.cfg file:
[include GET_PROBE_LIMITS.cfg]Then restart Klipper.
Credit to davidosmithII who came up with the idea and created the original macro to do it.
Now supports beacon in addition to bltouch and probe.
When you have a probe, you can also use it to help you level your bed.
This is performed using the SCREWS_TILT_CALCULATE command.
In order to use this, we need to set up a screws_tilt_adjust section in the config.
Here is an example:
# Bed screw adjustment
[screws_tilt_adjust]
screw1: 83,43
screw1_name: front left screw
screw2: 250,43
screw2_name: front right screw
screw3: 250,210
screw3_name: rear right screw
screw4: 83,210
screw4_name: rear left screw
screw_thread: CW-M4The screw_thread is the threading used on your bed-adjustment screws. Typical Ender 3 style beds use M4 threading and turn clockwise to decrease the bed height. M3-clockwise is also somewhat common.
If you are unsure, you can check your bed screws to verify the correct threading for your config.
The screw_name's can be anything you'd like. They are just for your own reference (and some UI stuff) There is no rules to how you may name them.
The number/order of the screws does matter however. Note the names I used for mine, your screws will also be referenced in that order so you should label yours accordingly (or at least use the correct coordinates) They are listed in a counter-clockwise order starting from the front-left.
The final step is finding the coordinates to use for each screw.
This process should be familiar if you followed my previous guides:
- Start Klipper and home the printer.
- Using your display controls/web interface or
G1commands, move the printhead until the probe pin is positioned above the front-left bed screw. - Note the X,Y coordinates either using your display/web interface or by executing the
GET_POSITIONcommand and checking the values fortoolhead - Repeat for the other bed screws until you have coordinates for all of them.
- If your printer does not have enough physical range to position the probe over a bed screw, just position it as close as possible and use those coordinates.
You will then use those coordinates in your screws_tilt_adjust config for the screw positions.
That's it for the configuration!
When you run SCREWS_TILT_CALCULATE it will probe all the bed screws and then tell you how much to adjust each to achieve level.
Keep in mind that even with a perfectly configured setup, adjusting one screw will cause some deviation in the others.
You will need to repeat this process several times. I recommend repeating until you are able to probe all screws twice without needing to make any adjustments.