Pick a beam length, then drag holes together to pin them.
Output vs input
X Y
Beams are rigid bars with evenly spaced holes. Pin holes together to make joints, anchor a hole to fix it to the table, drive it with a motor or ram, and watch the path with a tracer. The solver treats pins, anchors, stops and singularities as hard limits.
Drag a beam, triangle, editable plate, ram, motor, slider or gear out of the toolbox and drop it on the canvas. A slider has two selectable pieces: pin the blue bearing into a base or moving platform, then connect one or several links to the grey carriage's shared centre pin. A new editable plate is a box with four movable pin holes. Select it, choose whether outline clicks add or remove a segment in Properties, then click its outside edge. Drag a round pin handle near another hole to snap a connection. Select anything for a trash can beside it (Delete key works too).
Select (S) is for picking: click a part, Shift+click to add more, or drag a box — rightward is a window box (only parts fully inside), leftward is a crossing box (anything it touches). Reshape and stretch handles live on single selections; a group shows a shared panel instead. Move (M) is only for moving: drag a beam so a hole overlaps another's and release to snap a pivot; drag any part of a selected group to move the group. Double-clicking a part hops between the two tools.
Anchor fixes or releases a hole. Add a motor from Parts and pin its crank output into the mechanism, or add a ram. With Run stopped, manually move a selected ram or rotate a gear to each endpoint and capture Set current MIN/MAX in Properties. The dimensions update immediately, and Run reverses at the taught limits. Select a ram—or a part it drives—to see its solved amber motion range.
Open Items in use to select parts that are hidden underneath others. Clean extra pins removes only repeated locking constraints. If a particular part is still trapped, select it and choose Release selected, then drag it aside with Move. Both actions can be undone.
Under Reference image, open an image file or paste one with Ctrl/Cmd+V. Enter its real width in the current units, set its angle and opacity, and use Adjust position to drag it into place. Lock the image before adding and moving linkage parts. Reference images are embedded in saved mechanisms.
Trace tool drops a tracer on a hole — it draws the path that point travels as the mechanism runs.
Set your real hole pitch under Units & scale, then use Measure to click two holes and drop a live dimension. It keeps reading true while the mechanism runs. Click any part to open its Properties and type an exact length, angle or stroke.
The Analysis panel reads out mobility (degrees of freedom). Tick Velocity / Acceleration vectors to see motion arrows, or open the Output plot, set an output point, and sweep it through one full input cycle. Input & output reports travel, rotation, motion ratio and peak velocity/acceleration, and exports the whole cycle as CSV.
Linkage Lab never renders a pose with an open pin and never jumps to the other assembly branch: at a true fold the cycle stops just before it and says so. Shallow toggles that the drive can carry through are passed (with a transmission-angle warning), because they are poor leverage, not a wall. Dragging can't tear a joint either — past the reachable envelope the last valid pose holds — but you can still fold parts over to reconfigure them while building.
Scroll or pinch to zoom, drag empty space to pan, Shift+scroll over a beam to rotate it. Select one part and press Ctrl/Cmd+C, then Ctrl/Cmd+V to paste a loose copy; copying either half of a slider copies the complete slider. Ctrl/Cmd+Z undoes, Shift to redo. Save file, Open file, presets, undo and Reset all live in the top bar; Properties and Analysis share the panel on the right.
Name this mechanism. Linkage Lab will add the .json file extension automatically.