Situation

A B ME 315 design project: produce a 3D-printable display stand able to hold both Bandai Gunpla plastic model kits and Games Workshop miniatures. No stand on the market did both, and the reference product — Bandai's Action Base 5 — locked its arms with a gear-and-lever mechanism that restricts posing to discrete tooth angles.

Requirements: dynamic posing, an expandable baseplate carrying multiple arms, modular links, swappable holders for the two hobbies, tolerance of the forces applied while painting, and simple assembly.

Formally a three-person project. Omar was the sole designer and analyst of the final mechanism, covering CAD, FEA, printing, iteration, and the analysis write-up; a teammate produced the FEA of the reference Bandai joint used as the comparison baseline.

Actions

• Modeled the reference Bandai joint and the full redesign in SolidWorks — 12 parts and 3 assemblies.
• Ran static FEA studies in SolidWorks Simulation under a 4 N load representing a mounted model, evaluating von Mises stress and factor of safety.
• Identified from the reference analysis that the commercial joint carries its entire load through a single locking tooth, concentrating stress in a small contact region and creating a durability concern under sustained load.
• Redesigned the joint around a thumbscrew-and-washer bolted interface, distributing load across the whole joint face and replacing discrete tooth positions with continuous rotation.
• Replaced the fixed 3 mm pin with a universal 5 mm pin, making holders interchangeable, then designed three: a Gundam adapter with a deeper socket engagement, a 55 mm magnetic holder exploiting the magnets painters already fit to miniature bases, and a rubber-band holder for un-magnetized bases.
• Printed at 100% infill specifically so the physical part matched the solid-material assumption in the FEA.
• Iterated the parts through three print rounds, correcting dimensional fit — a connector lengthened 0.25 mm, a base connector thinned, several holes reduced. Corrections were estimated rather than measured, and converged after a single failed print.
• Costed the design against the commercial alternatives: ~176 g of resin at ~$0.04/g plus roughly $0.75 of fasteners, $7.79 total against $7.99–$9.99 for commercial stands, at 20 cm rather than the usual 10–15 cm.

Outcome

A working stand that holds both model types, poses continuously rather than in fixed steps, accepts interchangeable heads, and costs less than the commercial products it was benchmarked against while being larger and more versatile.

The redesign also moved the governing stress. With the gear tooth gone, the dominant load in the joint is no longer the weight of the model but the preload the user applies when tightening the bolt — a quantity set by the person assembling it rather than by the design. This was bounded against realistic use: the heaviest mainstream kit at roughly 2 lb, typical kits at 50–200 g, and painting forces under about 10 g.

Validation was by demonstration rather than measurement: posing through angles the gear design cannot reach, magnetic and rubber-band holders in painting use, and an informal overload check in which the arm was struck firmly — well beyond any load a modeler would apply — without moving.

Lessons / safety

The FEA results were not trusted, and were flagged rather than reported confidently. Two things did not reconcile. The reference joint presented a much smaller contact area under the same applied load yet returned stresses of a similar order, when a smaller area should have produced markedly higher stress. And the two studies loaded their geometry differently — in line with the force for the reference joint, perpendicular for the redesign — so the two factors of safety were never a like-for-like comparison. Time ran out before this could be resolved.

Recognizing that a result is unreliable is worth more than reporting it with false confidence, and the numbers are therefore not quoted here.

The material property was an estimate. The yield strength used was a rough figure for the printing resin rather than measured or datasheet data, which alone makes the absolute factors of safety indicative at best.

What the project still needs, in Omar's own order: a physical load test to check the analysis against reality; real material data instead of an estimate; the tool-free joint tightening the report recommends; and — the interesting one — a way to construct a methodologically valid comparison between two structurally different mechanisms without altering either design to suit the analysis.

Skills demonstrated

• SolidWorks part and assembly modeling
• Finite element analysis; von Mises stress and factor of safety
• Mechanism design and design-for-assembly
• Competitive teardown and benchmarking of a commercial product
• Design for additive manufacturing; dimensional tolerance correction
• Design iteration across three print rounds
• Cost analysis against market alternatives
• Critical evaluation of one's own analysis results

Evidence

In this folder: the full project report with 40 figures, the 14-slide presentation including FEA stress plots and the cost comparison, 12 SolidWorks parts, 3 assemblies, a SolidWorks Simulation study report, and 19 STLs recording all three print iterations by name.