Jerry
47 lines
2.0 KiB
Markdown
47 lines
2.0 KiB
Markdown
# 9. Spiral Staircase With Helical Handrail
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## Prompt
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Create a single STEP model of a miniature spiral staircase in millimeters.
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The staircase is centered on the origin and rises along Z.
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Add a central vertical column, diameter 14 mm and height 140 mm, with its bottom at Z = 0.
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Add 20 identical wedge-shaped stair treads arranged helically around the column. Each tread is 4 mm thick, has an inner radius of 10 mm, an outer radius of 62 mm, and subtends 24 degrees in plan view. The first tread is at Z = 4 mm, and each subsequent tread rises by 6 mm and rotates by 18 degrees around Z.
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Add a helical outer handrail tube of diameter 5 mm following radius 66 mm, starting at Z = 14 mm and ending at Z = 130 mm, making one full revolution around the staircase.
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Add 20 vertical balusters, each diameter 3 mm, connecting the outer end of each tread to the handrail.
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Add a circular base disk, diameter 90 mm and thickness 5 mm.
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Export as a STEP file.
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## Test Cases
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| Test | Expected result |
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| --- | --- |
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| STEP import | File imports successfully |
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| Main structure | Valid solid bodies or valid fused assembly |
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| Central column | Diameter 14 mm, 140 mm tall |
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| Column placement | Centered on Z-axis; bottom at Z = 0 |
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| Base disk | Diameter 90 mm, 5 mm thick |
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| Tread count | 20 |
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| Tread thickness | 4 mm |
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| Tread inner radius | R10 mm |
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| Tread outer radius | R62 mm |
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| Tread angular width | 24 degrees |
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| Tread rise | 6 mm per step |
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| Tread rotation | 18 degrees per step |
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| Helical progression | Treads rise and rotate together, not merely radial-patterned flat |
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| Handrail | Diameter 5 mm tube at R66 mm |
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| Handrail vertical range | Z = 14 mm to Z = 130 mm |
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| Handrail revolution | Approximately one full 360-degree turn |
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| Baluster count | 20 |
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| Baluster diameter | Diameter 3 mm |
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| Baluster relation | Each connects tread outer region to handrail |
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| Negative check | No missing rail; no flat circular stair pattern with no rise |
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