Rectangular Grid Calibration Options

This page documents all configuration options for the rectangular grid leveling strategy in Smoothie.

The rectangular grid strategy allows you to probe multiple points on your bed in a grid pattern to compensate for uneven bed surfaces.

This is particularly useful for:

  • 3D printing on warped beds
  • PCB milling on uneven surfaces
  • Any application requiring precise Z-axis compensation

Configuration Options

The following table lists all available configuration options for the rectangular grid leveling strategy:

Option Value Description
`true` The strategy must be enabled in the config, as well as the zprobe module.
`190` The distance from homed position to the right edge of the bed in mm.
`180` The distance from homed position to the top edge of the bed in mm.
`7` The size of the grid (X size == Y size), for example, 7 causes a 7x7 grid with 49 points. Must be an odd number.
`9` The X size of the grid. For X size != Y size. Must be an odd number.
`7` The Y size of the grid. For X size != Y size. Must be an odd number.
`0,0,0` Optional probe offsets from the nozzle or tool head in mm.
`false` If the saved grid is to be loaded on boot then this must be set to true.
`10` The initial_height (in mm) tells the initial probe where to move to in Z before it probes, this should be around 5-10mm above the bed.
`true` Human readable formatting of probe table.
`true` G29/G31/G32 will not work without providing XYAB parameters: XY - start point, AB rectangle size from starting point. “Two corners” not absolutely correct name for this mode, because it uses only one corner and rectangle size. This mode is designed for PCB milling when you work with board size different from bed size. More about this mode in PCB milling.
`0.5` Compensation normally is applied for all heights, with full power. If you set this setting to a height, the compensation will start to be applied less and less (linearly) until “height_limit” is reached. Any height before this setting will still be compensated fully.
`1` The compensation algorithm will stop working after this limit, starting from the “dampening_start” parameter. After the height goes through this limit, no more compensation will be applied.
M280 Automatically deploy a bltouch probe before the probing.
M281 Automatically stow the bltouch after probing.

For more information about leveling and probing, see:

Usage Notes

Grid size must always be an odd number (3, 5, 7, 9, etc.) to ensure there is a center point.

The more points you probe, the more accurate the compensation will be, but probing will take longer. When using only_by_two_corners mode, you must provide XYAB parameters with G29/G31/G32 commands.

This is particularly useful for PCB milling where you're working with different board sizes.

Example Configuration

V1 Configuration:

# Enable rectangular grid leveling
leveling-strategy.rectangular-grid.enable         true

# Bed dimensions (in mm from home position)
leveling-strategy.rectangular-grid.x_size         200
leveling-strategy.rectangular-grid.y_size         200

# Grid size (7x7 = 49 probe points)
leveling-strategy.rectangular-grid.size           7

# Probe offsets from nozzle (X, Y, Z in mm)
leveling-strategy.rectangular-grid.probe_offsets  0,0,0

# Initial probe height (mm above bed)
leveling-strategy.rectangular-grid.initial_height 10

# Save grid to load on boot
leveling-strategy.rectangular-grid.save           true

# Human readable probe table output
leveling-strategy.rectangular-grid.human_readable true

V2 Configuration:

[zprobe]
leveling = true

[cartesian grid leveling strategy]
x_size = 200
y_size = 200
grid_x_size = 7
grid_y_size = 7
probe_offsets = 0,0,0
initial_height = 10
save = true
human_readable = true
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