Bed Mesh
Mesh analysis

The slope is only part of the story

A large height range can describe a tilted flat surface, a curved surface, or a mixture of both. Fitted-plane analysis helps separate those observations.

Bed Mesh2 min read
An illustrative flat plane rising 0.100 millimetres in X, with zero range and RMS after fitted tilt is removed.
A simulated tilted plane in the visualizer. The original range is 0.100 mm; the fitted-plane residual range and RMS are zero.Bed Mesh interfaceView full-size image

Two meshes can have the same highest and lowest measurements while describing very different surfaces. One may rise steadily from left to right. Another may have high edges and a low centre. Their height ranges alone do not tell those stories apart.

A simple tilted example

Consider this illustrative grid in millimetres. Each column increases by the same amount, and each row is identical:

0.00  0.05  0.10
0.00  0.05  0.10
0.00  0.05  0.10

The original height range is 0.10 mm. A plane can describe every point in this example, so subtracting its fitted plane leaves essentially zero residual variation, apart from numerical rounding. The original range still correctly records what was measured.

What the fit measures

Bed Mesh fits a least-squares plane to the regularly spaced grid. The fitted X rise is the plane's change from the first column to the last. The fitted Y rise runs from the first row to the last. These directions follow input order; they do not identify the front, back, or a particular screw on your printer.

Residuals are the measurements after that plane is subtracted. Residual range records their spread, and residual RMS describes their typical magnitude around zero. Curvature or isolated features can remain even when the overall slope has been removed.

The same example after removing fitted tilt: a flat residual surface at zero, while the original height range remains 0.100 mm.
The same simulated grid with “Remove fitted tilt” selected. Original statistics remain visible below the residual chart. Screenshot: Bed Mesh.

Use both descriptions

Read original and residual values together. The original grid preserves the full measured surface. The residual view answers a narrower question: what shape remains once a simple overall tilt has been accounted for?

A fitted plane is a mathematical summary. It does not establish why a slope exists, whether the probe is accurate, or which mechanical change would help. Repeat measurements and knowledge of the printer still matter.

Try Remove fitted tilt in the visualizer's height-reference setting, then return to Measured height. The statistics and exported CSV continue to use the original data in either view.