Engineering · 2026
Table Shears: scissors you run with one push
A one-handed tabletop cutter: a bearing-mounted four-bar linkage and blades I made from 1084 steel.
The finished prototype on its cutting mat, lever up.
Members at Envision Unlimited, a Chicago day program for adults with intellectual and developmental disabilities, usually handed their art-class cutting to staff: scissors ask for fine finger control, arm control and holding the material in mid-air, all at once. Table Shears cuts that down to one table-mounted lever, gripped in the whole hand and driven by stronger muscle groups, that only moves forward or back while the material stays on the platform. In testing, a member cut with it and liked how easily it went through material.
- Role
- Team
I did the design and prototyping: the four-bar mechanism, the parametric Fusion 360 model, making the blades, and assembly. I also taught my teammates the shop processes. They led user research and documentation.
- Duration
- Winter quarter 2026
- Tools
- fusion-360, fdm-3d-printing, waterjet, manual-mill, heat-treating, reaming
- Skills
- mechanism-design, parametric-cad, human-centered-design, user-testing, prototyping
Goal & constraints
- The client's goal was independence. Members should cut on their own, with real scissors, not "safe" or childlike ones.
- Users struggled with grip, fine motor control and holding the material steady, but were comfortable with big arm motions.
- Cuts paper, felt, foam, fabric and thin cardboard; 12 × 12 in workspace; about 2.5 lb.
Process
- Cut the number of movements a user has to control. Instead of fingers, wrist and a free hand holding the work, there is one lever, gripped in the whole hand, that only goes one way or the other.
- The handle drives two connecting arms that swing the top blade down against a fixed bottom blade, so a large push becomes a small, controlled cut.
- Built the model in Fusion 360, fully parametric, so bearing size, blade size and material thickness could change without breaking it.
- Made the blades from 1084 high-carbon steel: waterjet-cut the profiles, milled the bevel, heat-treated them, then hand-sharpened on 325 and 1000 grit stones.
- Printed the lever, arms and joints in ABS, reamed the pivots to 3 and 7 mm, and pressed in seven ball bearings so the lever moves without extra force.
Result
Before and after
What I’d change
Cover more of the blade, and add a tilt so curved cuts are easier. A return spring would also let members cut with a push alone, since some can push or pull comfortably but not both.
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