This bed leveling and first-layer calibration model uses a series of concentric squares with rounded corners to evaluate bed leveling, Z-offset, and first-layer consistency across a large portion of the print surface.

Unlike traditional corner test patterns, this design creates a continuous path that progresses from the outside toward the center and then returns from the center back to the outside. This helps reveal inconsistencies in bed level, extrusion, flow rate, and motion performance while minimizing unnecessary travel moves.

Features Concentric square pattern with rounded corners Continuous print path Outside-to-center then center-to-outside toolpath Covers nearly the entire printable area Fits within a 200 mm × 200 mm envelope when printed with a brim Fast print time Minimal filament usage Easy visual inspection of first-layer quality Print Specifications Nozzle Diameter: 0.4 mm Layer Height: 0.20 mm Total Layers: 4 Model Height: 0.80 mm Recommended Print Speed: 20–50 mm/s Infill: Not Required Supports: None What to Look For

A properly calibrated printer should produce:

Consistent line width Smooth line adhesion Uniform spacing between paths No gaps between extrusions No nozzle dragging No excessive squish or elephant footing

If some areas appear thinner, wider, rougher, or fail to adhere properly, adjust bed leveling and/or Z-offset and repeat the test.

This model is intended as a quick diagnostic tool for verifying bed tramming, first-layer quality, and overall build surface consistency.