# VectorPaint single-pulley rope routes: join two straight runs through one upper semicircle

Language: en
Canonical: [VectorPaint single-pulley rope routes: join two straight runs through one upper semicircle](<https://allluckly.cn/en/guides/vectorpaint-single-pulley-rope-tangent-route/>)
中文：[中文 HTML](<https://allluckly.cn/guides/vectorpaint-single-pulley-rope-tangent-route/>)
English: [English HTML](<https://allluckly.cn/en/guides/vectorpaint-single-pulley-rope-tangent-route/>)
Published: 2026-11-12T00:00:00+08:00
Modified: 2026-11-12T09:43:29+08:00
Author: Bison

Draw wheel, axle, support and an open rope route, checking tangency and occlusion without load analysis or lifting instructions.

English translation of the [Chinese original](<https://allluckly.cn/guides/vectorpaint-single-pulley-rope-tangent-route/>), translated on 2026-11-12. Original publication dates, attribution, code and version notes are retained.

Draw a side view of a fixed-axis wheel with rope rising on the left, passing over the upper half and descending right. The task is one continuous open route, not force, efficiency or lifting design. VectorPaint supplies static paths and layering; units are pictorial and no pulley is fabricated or suspended load operated.

## Set the viewing plane and route scope

Use a 1400×1600 canvas with the wheel centre above the midpoint, separating support, wheel, rope and labels. [OpenStax’s simple-machine diagrams](<https://openstax.org/books/college-physics-2e/pages/9-5-simple-machines>) distinguish single and multiple wheels. Borrow only the selected single fixed-axis appearance, without applying ideal conclusions as guarantees about equipment. Label ends A and B solely for tracing, not input/output force or suspended mass. Keep both free ends inside the frame so their connection state remains inspectable.

## Set centre, radius and straight runs

In the checking diagram, use centre (700,600) and rope-centreline wrapping radius 250. Tangency points are (450,600) and (950,600); straight runs at x=450 and 950 descend to y=1300. These are construction references. The wheel edge can sit slightly inside the rope centreline to suggest rope thickness; those are not one identical radius. If exact entry is unavailable, place approximately against a grid and retain the diagram label. Check equal 250 offsets before drawing the curve so neither side floats away.

## Wrap only the upper semicircle with vertical tangents

Trace upward from the left end to its tangent point, across the upper semicircle through top point (700,350), then downward from the right tangent point to its end. Both endpoint tangents are vertical, matching the straight runs; no right-angle kink belongs at the top. Use available arc or manual curve methods with few nodes and controlled tangents, not an assumed automatic wrapping tool. A Bézier approximation remains approximate rather than exactly constant-curvature. There is no lower-half rope arc or bottom crossbar joining ends: the route stays open. An optional centreline calculation gives two straight runs of 700 each plus semicircle length 250π: total 1400+250π≈2185.4 drawing units. This measures the specified diagram only, not real rope procurement or safety allowance.

## Separate wheel, support and rope depth

Draw the wheel disc, central axle cap and support rising from the axle region to a schematic mount; the support is not a third rope. Choose a depth convention with near support partly covering the disc while rope remains readable at its rim, then order objects accordingly. If support hides tangency points, simplify its outline explicitly rather than deleting rope. Keep the cap centred despite highlights. Decorative concentric circles are not extra pulleys, and no bearing, groove or support capacity is assessed.

## Keep styling from moving the route

Once the centreline passes, use a consistent rope stroke, perhaps warm against a cool-grey wheel; monochrome readability still depends on placement. Stroke edges extend beyond the centreline radius, so do not call tangency coordinates wrong from the outermost antialiased pixel. Check the path centre, not raster fringe. Widen faint rope carefully while retaining support gaps. Equally strong highlights on both sides can create a three-rope illusion. Any decorative end knot is pictorial only, with no real knotting, fastening or load instructions.

## Separate lower-arc and broken-tangent errors

In one copy, replace the upper arc with a lower arc: the downward straight runs now reverse at the tangent points rather than following the specified over-top route. Merely having an arc is insufficient. In another, retain the upper arc but shift the right run one grid space right to expose a broken tangent join. Name these separately: repair wrapping direction for the first and coordinates/connection for the second. These are diagram comparisons, not rope-motion or wheel-rotation experiments. A/B labels imply no real force direction.

## Trace the same rope after export

Save and open a PNG, tracing A through left straight run, upper arc and right run to B. Hide shadow/labels to confirm only two free ends, then restore explanations. For a broken arc inspect occlusion and nodes; for a floating run check tangency coordinates rather than thickening over gaps. Hide ordinary drawn references deliberately and inspect whether native grids appear in the actual export. Open SVG/PDF separately; if a curve becomes visibly polygonal, inspect source and display without guaranteeing identical accuracy in all viewers.

## Finish with route and scope checks

Accept one wheel, one shared centre, two vertical runs, one upper semicircle and two free ends; decorative axle rings do not increase wheel count. Recheck 700−450=950−700=250 and top y=350. Continuity establishes only the static drawing’s route, not actual friction, tension, force savings or load safety. Retain the no-force-analysis notice and separate error/repair records. Engineering lifting design needs real data and an appropriate professional process; this illustration exercise is no substitute.

## Related tutorials and sources

[VectorPaint equal-pulley belts: join common tangents to outer semicircles](<https://allluckly.cn/en/guides/vectorpaint-equal-pulley-belt-outline/>), [VectorPaint gradients: give a circle a clear light direction](<https://allluckly.cn/en/guides/vectorpaint-gradients/>).

Checked on November 12, 2026: VectorPaint public version 1.0.8, requiring iOS / iPadOS 17.0 or later. Scope follows the [official App Store](<https://apps.apple.com/cn/app/id1587272880>) and [Apple public lookup](<https://itunes.apple.com/lookup?id=1587272880&country=cn&entity=software&timestamp=20261112>). Manual exercises use controls actually available in your installed version; external calculations, written records and diagrams imply no built-in automatic analysis. No step-by-step physical-device, private-file or all-export-environment testing is claimed.