Interactive HTML5 Canvas simulation of a vernier caliper that supports non-standard configurations (n VSD = m MSD).
- Configurable scales — set any MSD value, n VSD = m MSD relationship, and object size
- Visual least count proof — overlays both scales from a common zero and shows the gap at each vernier mark; the smallest gap = LC. No formula needed.
- Correct general LC formula — LC = gcd(n, m) / n × MSD (Bezout's identity), not the naive |1 MSD - 1 VSD|
- Geometric reading method — Reading = MSR + m(MSD) - n(VSD), which works for all vernier types unlike the standard n × LC shortcut
- Realistic caliper rendering — steel-look bars, jaws, draggable vernier, zoom/pan, touch support
- Coincidence highlighting — animated red glow on the aligned main + vernier tick pair
- Drag the green vernier strip to slide the jaw
- Scroll to zoom in/out
- Drag background to pan
- Double-click to snap vernier to object size
- Adjust parameters in the top bar and click Apply
Most textbooks only cover the simple case (e.g., 10 VSD = 9 MSD) where LC = |1 MSD - 1 VSD|. For non-standard configurations like 10 VSD = 7 MSD, this naive formula gives 0.3 mm — which is wrong. The true LC is 0.1 mm, derived from Bezout's identity / GCD.
Similarly, the standard reading formula MSR + n × LC fails for non-standard verniers. The correct geometric method (MSR + m·MSD - n·VSD) works universally.
This simulator makes both concepts visually obvious.