# VectorPaint hourglass schematics: connect two bulbs through one neck

Language: en
Canonical: [VectorPaint hourglass schematics: connect two bulbs through one neck](<https://allluckly.cn/en/guides/vectorpaint-hourglass-bulbs-neck-sand-schematic/>)
中文：[中文 HTML](<https://allluckly.cn/guides/vectorpaint-hourglass-bulbs-neck-sand-schematic/>)
English: [English HTML](<https://allluckly.cn/en/guides/vectorpaint-hourglass-bulbs-neck-sand-schematic/>)
Published: 2026-11-11T00:00:00+08:00
Modified: 2026-11-11T09:40:26+08:00
Author: Bison

Separate glass outline, connected cavity and sand piles, checking a stationary state without inferring timing accuracy or granular flow.

English translation of the [Chinese original](<https://allluckly.cn/guides/vectorpaint-hourglass-bulbs-neck-sand-schematic/>), translated on 2026-11-11. Original publication dates, attribution, code and version notes are retained.

An hourglass is more than two triangles touching at their points. Draw a simplified upright longitudinal schematic, checking cavity continuity through a neck before adding sand. Hand-drawn piles and a thin stream are a stationary depiction, not a minute or other duration calculation, granular simulation, or proof of equal capacity or manufacturability.

## Give envelope and neck one axis

Use a portrait canvas with a shared vertical axis, pale upper/lower bulb envelopes and room for supports. Keep finite neck width and continuous left/right contours. Near-mirrored silhouettes are a composition choice, not equal-capacity measurement. Separate envelope, cavity references, sand and supports before reflections or grain. Round bow-tie-like triangular sides. If it resembles stacked bottles, inspect whether independent bottle bottoms block the join. The manual axis is a reference, not an automatic symmetry constraint.

## Do not cap the neck passage

Use pale inner contours with separation through the neck. A checking path should run from upper to lower cavity without crossing sidewalls or a horizontal cap. Hide sand to inspect the passage before restoring it. Any enlarged neck detail needs its source location and stated scale; enlargement does not add another opening. Omit real wall-thickness variation rather than treating contour gaps as manufacturing tolerances. Repair fill/order for a solid-looking neck instead of adding a dark line that pretends it remains open.

## Separate upper surface and lower pile

Depict remaining upper sand with a roughly level surface narrowing toward the neck, and a small lower pile pointing upward with its base on the cavity floor. Keep both within glass. Use pale-brown masses separated from the exterior, retaining glass identity. Screen area is not physical volume, and upper surface height does not give remaining seconds. If both piles resemble identically directed caps, distinguish upper sand converging downward from a lower mound rising upward. Texture dots cannot repair that directional error.

## Connect the selected state with one stream

An optional narrow stream runs from the neck exit to the lower mound near the same axis, without unexplained sideways turns. Do not let it fill the whole neck and obscure the passage. It indicates a selected state, not measured flow or fluid calculation through speed arrows. A stopped-state variant needs the stream removed and wording updated; do not claim no flow while drawing continuous falling sand. Check start, end and wall clearance before sparse particles. Their count is no timing unit.

## Separate supports and glass highlights

Join top/bottom supports with side posts, optionally behind glass, not through the sand cavity. Upper-left light uses narrow broken glass reflections while preserving the neck and sand masses. Reduce full white borders for a metallic-bottle appearance or establish lower contact for unsupported bulbs. Post count belongs to this design, not all hourglasses. Hide highlights to inspect cavity, then ensure restored light does not cap the neck. Decorative grain is optional; a thick post must not conceal an unconstructed passage.

## Test continuity with a capped copy

In a separate incorrect copy add a closed material strip across the neck while retaining sand shapes. Cavities are now separated, so the same flow-through explanation no longer applies. Identify and remove the capping object rather than drawing the stream through it. Label correct and wrong versions separately: similar silhouettes do not establish equal connectivity. This edits a diagram, not a real hourglass or blockage experiment. It makes no claim about actual grain jamming because real flow conditions were not measured.

## Inspect neck width versus stream in output

Save and inspect PNG cavities, both neck sides and stream endpoints at use size. Enlarge presentation or add a detail if the neck collapses to a point; do not redefine continuity as zero width. Recover a lost stream locally without thickening it into a column. Inspect glass/background relationships; white patches are not automatically transparent. Hide unwanted axes/tracing guides while retaining official contours and sand. For another format isolate glass, sand and masks in a copy. There are no timing numbers to alter, and the editable original remains preserved.

## Review passage, state and occlusion

For stacked bottles inspect a capped neck; for sand outside inspect cavity boundaries; for stopped/flowing contradictions inspect the selected state; for closure at small sizes inspect neck width and output. Trace upper-to-lower continuity after each repair rather than only mirrored silhouettes. Retain cavity sketch, state note, supported view, capped control and output. This is a stationary appearance/section exercise, not grain simulation, equal-volume proof or precision timer design, and establishes no real stability, flipping performance or timing accuracy.

## Related tutorials and sources

[VectorPaint cup cutaways: distinguish walls, cavity and handle opening](<https://allluckly.cn/en/guides/vectorpaint-cup-cutaway-cavity/>), [VectorPaint detail callouts: match enlarged areas to their source](<https://allluckly.cn/en/guides/vectorpaint-detail-callout/>).

Checked on November 11, 2026: VectorPaint public version 1.0.8, requiring iOS / iPadOS 17.0 or later. Capability 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=20261111>). This is an original manual exercise; use controls available in your installed version and actual file state. External calculations, records and diagrams do not imply new automatic analysis. No step-by-step physical-device, private-file or all-export-environment testing is claimed.