Customizable Linkage Jack Teaching Prototype - Parametric Tilting-Column Mechanism

A customizable, parametric mechanical linkage-jack teaching model built entirely in TrueGeometry Playground. One driving variable, $TILT, sets the column angle and the whole 63-part mechanism re-poses: base on casters, A-frame posts, four-bar parallelogram linkage, tilting lift column with ground wheel, handle, tie rod and load pad.

Teaching model, not load-rated equipment. UNPRINTED, UNTESTED PROTOTYPE: every fit is CAD-verified inside TrueGeometry Playground (native high-precision mesh collision checks at $TILT = 75 / 80 / 85 plus a full bounding-box interference audit across all 63 parts), but no physical unit has been printed, assembled or loaded. Press-fit caps (0.1 mm radial interference - the only intentional interference) and bonded joints (posts, cross members, caster brackets, pad) are design intent, not proven hardware. If you print it, treat it as a mechanism demonstrator, start with light loads, and please share a Make - community test prints genuinely help improve these designs.

Files:

- jack_assembly_v6.stl - full 63-part assembly, upright as designed (main file)

- jack_components_native_v6.zip - all 63 individual component STLs (native Playground exports) for printing

- jack_linkage_recipe.txt - the full parametric Playground recipe

- jack_playground_guide.pdf - how to open, run and customize, verified poses, print notes

Customize in TrueGeometry Playground: open the live model, tick Auto-Update 3D and drag the $TILT slider between 75 and 85 (the verified CAD working range; pad-center travel +7.9 mm vertical). More sliders: $LP link length, $LCB column length, $S rocker spacing, $TOE handle toe, $TRL tie-rod length.

Live model (open and customize): https://pro.truegeometry.com/CoreWebGLTG/KBEAgentHTTP.html?cadcommand=cmd_6e99db05-7d4.txt

Full TrueGeometry Playground commands, mechanism math and step-by-step assembly order in the blog article: https://blog.truegeometry.com/0_0_0_0/blogs/post-d062e7da.html

Printing: PLA or PETG, 0.2 mm layers, plates printed flat, no supports. 63 parts; pins rotate in 0.6 mm-clearance bores; caps press on.

An original TrueGeometry adaptation inspired by the DIY linkage-jack video "Hydraulic Jacks are Out? DIY Mechanical Jack" (Kineticist, YouTube Shorts) - not a replica: linkage layout, proportions, retention and the parametric recipe are our own.

License: CC BY-NC 4.0 - for students, teachers and makers; commercial use requires consent from TrueGeometry.