CAD · Render

Patent Wrench Case Study

We have a soft spot for old patents and mechanical ingenuity, and we recreate them to keep our modelling sharp for client work. This study reconstructs Frederick H. Seymour's 'Monkey Wrench', U.S. Patent No. 273,170, from the single-page patent drawing.

Original 1883 patent drawing of Seymour's monkey wrench, US 273,170 — Patent US 273,170 reference drawing

From patent drawing to CAD

The mechanism is simple, but the recreation is a satisfying challenge, a good afternoon exercise in reading an old drawing and rebuilding it accurately. The tool is composed of four basic parts. A twisted handle gives it greater rigidity than a plain bent U-loop would. The thread is machined directly into the handle stock, and an adjustment nut travels along it; that nut carries a notch that catches the lower moving jaw and a knurled band that improves grip while adjusting.

CAD render of the recreated 1883 monkey wrench, showing its twisted handle, threaded adjustment nut and adjustable jaws

Assembly and render

The upper fixed jaw is held in place by widening the bent handle stock after insertion. To practise scene setup and materials, we took the finished model into Blender and rendered the wrench resting on a table beside the patent sheets.

Rendered monkey wrench resting on a table beside the patent sheets

Services used

CAD modelling from reference
Mechanism reconstruction
Material and scene rendering (Blender)

Deliverables

CAD model of the wrench assembly
Reference-matched render

Notable technical detail. The twisted handle is the clever bit: it stiffens the tool through geometry alone, without adding material, exactly the kind of detail that makes historical patents worth studying.