One crank raises all four legs. No motors, no electronics.
Crank turns: 0.0 Desk height: 28″
Drag the red crank handle, use the slider, or hit Spin. The lift shown is compressed for the demo — see the math note below.
One crank under the desk turns a shaft. At each corner, a wooden bevel gear drives a vertical threaded rod — a screw jack — hidden inside the leg. A chain or a second gear train links all four shafts, so one turn lifts everything in sync and the top stays level.
The idea is borrowed from a Fine Woodworking variable-height assembly table that does the same thing with trailer jacks and a bicycle chain. This version is just prettier, and all wood.
Before building a desk, I made a laser-cut gear toy to test the mesh: three gears, 32 teeth driving 18 driving 18, true involute flanks, module 3 mm, cut from 1/4″ stock. The gears on this page are the same geometry as the toy. Lesson number one: cut one gear pair first and check the mesh before cutting everything.
Half of woodworking is making the tools to make the other half. The gear toy is a tool for making the desk.
With a 2 mm-pitch screw thread, one crank turn lifts the desk about 3.6 mm — the 32-tooth crank gear speeds the output up by 32/18, so each turn spins the screw about 1.8 times. Full range, 28″ to 48″, takes roughly 140 turns. Slow, but that is the point: a screw jack holds its height with no power, and you feel every millimeter.
Not built yet. The gear toy is the first test. Someday, a garage, a crank, and the best woodshop in all of Bellevue.