Recent Blogs
Roberts Linkage Mechanism: How It Works, Diagram, Formula, and Uses in Straight-Line Motion
Roberts Linkage explained — a four-bar straight-line mechanism used in robotics, prosthetics, and instrument design. Geometry, formulas, and a worked example.
Rigid Origami Mechanism Explained: How Single-DOF Miura-ori Folding Works, Parts, Formula & Uses
Rigid origami folds flat panels along hinge creases without bending the faces. Used in aerospace deployables, medical stents, and architectural shading systems.
Rhombic Drive Mechanism: How Philips' Counter-Rotating Stirling Linkage Works, Diagram & Uses
Explore a symmetric rhombic drive with counter-rotating cranks and four equal links. Calculate rhombus height limits and shaft angular speed.
Quadruplanar Inversor: Ideal Circle-Inversion Map
Quadruplanar Inversor explained — how this 4-bar inversion linkage converts circular motion to straight-line travel for drafting tools, optics jigs, and lab gear.
Quadrant Catch Hand-Gear Form B: Ideal Reduction Ledger
Quadrant catch hand-gear form B explained — how the spring-loaded pawl locks elevation arcs on field guns and survey theodolites, with formulas and a worked...
Quadrant Catch Hand-Gear Form A: Declared Arc-Index Ledger
Quadrant Catch Hand-gear Form A explained — how the toothed quadrant lever locks naval gun elevation, with diagrams, formulas and restoration examples.
Two-Oblique-Bar Press Motion: Exact Toggle Geometry
Two oblique bars convert horizontal input into vertical press motion. See the geometry, formula, worked example, and trade-offs for press tooling builders.
Single-Rod Hydraulic Cylinder: Ideal Net Rod Load and Nominal Stress
Piston Rod explained — how it transmits force from piston to crank, sizing rules, buckling limits, and real examples from diesel engines to hydraulic presses.
Peaucellier-Lipkin Linkage: Exact Straight-Line Inversor
Explore the Peaucellier-Lipkin straight-line linkage. Calculate the inversion constant, line offset and ideal output stroke from link lengths and driver swing.
Pawl-and-Elbow Lever Feed: Brown Movement 155
Explore Brown’s elbow-lever pawl feed. Calculate ideal angle per stroke, total wheel turns, average speed and elapsed time from whole-tooth indexing inputs.
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.
Parallel Ruler (Form 1): Exact Equal-Arm Translation
Explore an equal-arm parallel ruler. Calculate longitudinal shift, line separation, enclosed area and ideal parallelism from pivot spacing, arm length and 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.
Overconstrained Linkages: Generic Mobility Count Limits
Compare the generic spatial mobility count with an entered observation. Learn why special constraint dependencies allow overconstrained linkages to move.
Metal Expansion Joint: Free Pipe-Growth Worksheet
Explore axial movement in a metal bellows and calculate free pipe thermal growth. The result is a movement estimate, not an expansion-joint rating.
Four-Leg Chair Equalizer: Qualitative Posture Viewer
A qualitative posture viewer for a four-leg chair equalizer, showing how the connected front-leg joint permits opposite rocking directions on an uneven floor.
Kinematic Coupling: Contact-Count Calculator and Limits | FIRGELLI
Compare nominal contact and freedom counts for a coupling. Counts alone do not prove exact constraint, stability, load capacity or positioning repeatability.
Kempe’s Universality Theorem: Working Linkage Example
Explore Kempe’s universality theorem through a rigid-bar Peaucellier linkage. See a circle become a straight line and calculate the illustrated tracing motion.
Crank and Slotted Lever: Sweep-Time Calculator | FIRGELLI
Calculate slotted-lever sweep angles, unequal timing intervals and cycle time from crank radius, center distance and speed. The attached ram has separate turning points.
Ideal Machine: Force, Travel and Work Calculator | FIRGELLI
Explore lossless force-travel reciprocity and equal input/output work. Real mechanism geometry, losses and load capacity are not calculated.
Hoecken Linkage: Link-Length Scaling and Model Limits | FIRGELLI
Explore approximate straight-line linkage geometry and calculate scaled link lengths. Velocity variation, usable stroke, full-cycle closure and payload are not verified by this tool.
Hoberman Sphere: Folding Animation and Diameter Calculator
Explore a Hoberman-style sphere built from rigid bent scissor links. Watch its joints fold and calculate diameters for the illustrated equal-arm geometry.