Write the limits. Get the part that meets them.

Simulated: two PETG gripper jaws, each held at its left end and pushed sideways at its face, drawn bent by their true deflection and coloured by stress. The 4 mm jaw on the left bends far and is red at its root; the 6.625 mm jaw on the right bends little and stays blue. — Simulated. A gripper jaw at 4 mm and at 6.625 mm under the same 40 N grip, bent by its true deflection.

Case study · a gripper jaw

At 4 mm the jaw bends 8.7 mm.

One jaw of a parallel gripper: PETG, 60 mm long, held at its root by the carriage, with 40 N of grip spread over its face. The study asks for at most 2 mm of deflection and at most half of PETG's yield. The first sweep, three meshes from 2 mm to 1 mm, fails both.

deflection at the tip (the limit is 2 mm): 8.72 mm
von Mises stress (the limit is 23 MPa): 25.5 MPa
mesh levels, quadratic tetrahedra: 3
GCI of the deflection across the levels: 1.42%

Simulated: a 4 mm PETG gripper jaw held at its left end and pushed sideways at its face, drawn bent by its true 8.7 mm deflection beside its unbent outline, red with stress at its root. — ProvenanceFile `cloud://home/user-commandagi/case-studies/fea-studies/gripper-jaw/Jaw.study.tsx`Run `runs/20261104t163537z-2ire`Tool `commandagi validate --run --revise`Ran on This computer (dell-gb10-1): the fea kernel in its container; the part built by the 3D service on AWS LambdaWhen 2026-11-04

The planner

Seven tries to the thinnest jaw that passes.

The study lets the planner change one parameter, the jaw's thickness, from 3 to 12 mm. It tries the strong end, then halves the gap between a pass and a fail. Each try is a sweep of three solves, on the record. It stops at 6.625 mm, 0.125 mm above the last fail, and writes the new thickness into Jaw.3d.tsx.

See the validation planner

The tip's deflection at each thickness the planner tried

4 (start)8.72 mm

120.341 mm

81.12 mm

62.61 mm

71.65 mm

6.52.06 mm

6.751.84 mm

6.6251.95 mm

数値

The tip's deflection at each thickness the planner tried
Thickness tried (mm)	Deflection at the tip
4 (start)	8.72 mm
12	0.341 mm
8	1.12 mm
6	2.61 mm
7	1.65 mm
6.5	2.06 mm
6.75	1.84 mm
6.625	1.95 mm

ProvenanceFile cloud://home/user-commandagi/case-studies/fea-studies/gripper-jaw/Jaw.study.tsxRun runs/20261104t163651z-0r0jTool commandagi validate --run --reviseWhen 2026-11-04

The result

At 6.625 mm, every check passes.

The last sweep holds: deflection and stress are under their limits, and the checks that make a result worth reading pass too. The reactions balance the load, the residual is small, the mesh converges, and the stress peak at the clamp's edge is named as a number of the mesh, not of the part. Beam theory for the same cantilever gives about 1.98 mm, so the solve agrees with the textbook to 2%.

deflection at the tip: 1.95 mm
von Mises stress, 40% of the limit: 9.25 MPa
nodes on the finest mesh, solved in 5.8 s: 44,910
GCI of the deflection: 0.42%
solves in 8 sweeps, in 84 s: 24
of the load left unbalanced: 1.1 × 10⁻⁶

Simulated: the revised 6.625 mm PETG gripper jaw under the same push, bent by its true 1.95 mm deflection beside its unbent outline, blue and green: its stress stays low. — ProvenanceFile `cloud://home/user-commandagi/case-studies/fea-studies/gripper-jaw/Jaw.study.tsx`Run `runs/20261104t163651z-0r0j`Tool `the fea kernel: Gmsh and CalculiX`Ran on This computer (dell-gb10-1)When 2026-11-04

Study your own part.

A study is one file beside the part. Write it, or ask an agent to, and let the planner find the part that holds.

Open the gripper study Get started See engineering