Method

Press and return strokes are recorded at 0.005 mm displacement steps on a calibrated bench. intake-qc-v1.4 is the retention authority for this build, including integrity, target-speed-cohort, and replicate-agreement gates. Its retained-cohort RAMP repeatability check is advisory only: “ACCEPT + RAMP REVIEW” never changes retention or metric values. Scalar landmarks/markers are arithmetic means of per-run detections calculated at full precision. Averaged visualization traces are built separately and are not re-analyzed to create those scalar landmarks/markers; a marker therefore need not lie on a feature of the averaged trace. Rounding is presentation only.

Weight-family descriptors. Collapse force is the detected mechanical collapse peak. Ramp is the pre-collapse buildup over the baseline-relative 10–90% rise (seating transient excluded). Pre-collapse work is the one-way mechanical work integral from the start of the press to Collapse. Tactility-family descriptors. Drop = Collapse − Valley in gf. Steepest drop is the fastest force loss over any 0.10 mm window between Collapse and Valley. Drop rate divides Drop by the collapse-to-valley distance. Snap % = Drop / Collapse × 100. Detected force-wall onset is the first point past the valley where force rises by more than 1% of its current value per 0.005 mm step, sustained for three consecutive steps. Work converts to SI as 1 gf·mm = 9.80665 µJ. Collapse force, Ramp, Pre-collapse work, Drop, Steepest drop, Drop rate and Snap % are mechanical descriptors of the measured curve. Their pilot associations do not establish independent causal contributions.

Assembly scope. Detected force-wall onset is an operational proxy from the complete measured test assembly. It is not nominal dome height, physical switch travel, actuation travel, or a universal contact position. In the comparison tab, earlier onset means the rig reached the force wall with less measured displacement. All dome baselines use 0.00 mm added precompression, so this effect is present in the measured assembly without intentionally precompressing the dome; it is not by itself verification of an advertised travel claim. Group summaries describe only the tested specimens and are not manufacturer specifications. The fixed Topre production reference is the equal-weighted mean of nine released HHKB Pro2 and Realforce R1, R2, RGB, and GX1 dome datasets. Recorded turnaround range (test limit) is the minimum–maximum of the maximum press displacement captured across retained runs (one exact value when identical). It describes acquisition extent only and is never physical travel. If no force-wall meets the method, the force-wall field remains “Not detected”; a turnaround is never substituted.

Pilot-derived indices. Weight Index is this dome’s weight percentile compared with the other domes tested. Tactility Index is this dome’s tactility percentile compared with the other domes tested. Each index uses one full-precision input—Collapse force for Weight Index and force Drop for Tactility Index; correlation coefficients and supporting descriptors are not calculation weights. The 25-dome pilot identified those inputs as the strongest matches to perceived weight and collapse sharpness; the indices are not predicted 1–10 ratings. Part-assembly records are shown as Not calibrated. A low tactility index does not mean linear/off. Force-wall onset is separate and never enters either index. Full pilot method and data. Beyond Snap Ratio, Preprint 2.1.

Documentation: public method, interpretation, provenance, limitations, and update procedures are included with this release in the Force Curve Bench documentation.