Recent Blogs
Proportional Dividers: Exact Similar-Triangle Scaling
How proportion compasses and hyperbola-drawing linkages work, with the geometry, real shop scenarios, and a worked example for pattern-makers and drafters.
Section Liner Mechanism: How the Pawl-and-Rack Indexing Works, Parts, Uses, and Hatching Formula
Section Liner explained — how draughtsmen use this drawing tool to hatch parallel section lines fast and consistently in mechanical and architectural drafting work.
Roller Parallel Ruler Mechanism Explained: How It Works, Parts, Diagram and Marine Navigation Uses
How a Roller Parallel Ruler works, the geometry behind its tracking accuracy, and why marine navigators still use it on paper charts today.
Tracing Bar: Guides, Pivots and Entered-value Comparisons
Explore how guides and pivots constrain a tracing bar. Add entered offsets, scale a length and convert units; the calculator does not solve the traced...
Parabola Drawing Instrument: Exact Focus-Directrix Construction
Explore the taut-string and tee-square parabola construction. Calculate rim sag, half aperture and equal focus/directrix distances from aperture and focal length.
Drawing Instrument (form) Mechanism: How It Works, Parts, Diagram & Error Calculator
Explore drawing-compass geometry and combine entered standard uncertainties. Compare drawing radius, circumference and equivalent full-size dimensions.
Cyclograph: Three-Rule Circular Arc Mechanism and Coordinate Calculator
See a three-rule cyclograph draw a circular arc using two fixed guide pins. Calculate radius, arc length and pencil coordinates from chord spacing and rise.
Three-part Parallel Ruler: Arm-length Mismatch Comparison
Explore the equal-arm parallel-ruler arrangement and compare three entered length mismatches. Percentages are dimensional comparisons, not angular-error predictions.
Parallel Ruler (Form 6): Ideal Alternating Walk Sequence
Explore parallel-ruler motion. Calculate the components of one equal-link transfer and the total perpendicular advance for repeated transfers at a fixed angle.
Parallel Ruler (Form 5): Hiscox Slotted Crossed Bars
Explore Hiscox’s slotted parallel ruler with equal crossed bars. Calculate ruler separation, sliding-end span and center-to-end distance from bar length and angle.
Parallel Ruler (Form 4): Ideal Repeated-Line Transfer
Explore repeated transfers with an equal-link parallel ruler. Calculate perpendicular step size, full placement count, covered distance and final excess.
Parallel Ruler (Form 2): Hiscox Equal-Link Pivot Path
Explore Hiscox’s equal-link parallel ruler. Calculate longitudinal shift, perpendicular separation and circular pivot travel from link length and opening angle.
Drawing Pantograph: Exact Homothetic Scale
Explore a rigid-link drawing pantograph. Calculate pencil-to-tracer scale, pencil-path length and ideal area scale from a reduction ratio.
Trammel of Archimedes: Ellipse Geometry Calculator
Explore perpendicular sliders with a tracing point between them. Calculate ideal semi-axes, area and eccentricity from point-to-slider distances.