1 Lettering
One face for everything on a drawing: osifont, an ISO 3098 type B upright, one weight, capitals. Its stem is 0.101 of the cap height, so the stroke is h/10 as the standard asks. Sizes are set by cap height h, from the ISO 3098 series 1.8, 2.5, 3.5, 5, 7 mm: font size = h / 0.7373. Hierarchy comes from size alone, never from weight or colour. Reading text on the web pages is B612; it never appears inside a drawing view or a block.
| Role | Face | Cap h mm | Font size mm | Font size px | Stroke mm | Tracking | Case | Notes |
|---|---|---|---|---|---|---|---|---|
| Title block field label | osifont 400 | 1.8 | 2.441 | 9.28 | 0.18 | +0.02 em | caps | DRAWN, DWG NO., SCALE |
| Small note in a view, flag numeral | osifont 400 | 1.8 | 2.441 | 9.28 | 0.18 | 0 | caps | |
| Dimension text | osifont 400 | 2.5 | 3.391 | 12.88 | 0.25 | 0 | caps | unidirectional, centred in a break in the line |
| Note, table cell, title block value | osifont 400 | 2.5 | 3.391 | 12.88 | 0.25 | 0 | caps | line pitch 1.5 h |
| Balloon numeral, zone character | osifont 400 | 2.5 | 3.391 | 12.88 | 0.25 | 0 | caps | |
| Sheet title (title block), view label, table caption | osifont 400 | 3.5 | 4.747 | 18.04 | 0.35 | 0 | caps | scale on a second line at h 2.5 |
| Drawing number, revision letter | osifont 400 | 5.0 | 6.781 | 25.77 | 0.50 | 0 | caps | revision letter in redline |
| Section and detail letters at the cutting plane | osifont 400 | 5.0 | 6.781 | 25.77 | 0.50 | 0 | caps | |
| Cover title (web only) | osifont 400 | 7.0 | 9.494 | 36.08 | 0.70 | 0 | caps | |
| Reading text (web, outside the drawings) | B612 400 | 3.00 | 3.947 | 15.00 | — | 0 | sentence | line height 1.62, measure 66 ch |
| Code (web) | B612 Mono 400 | 2.50 | 3.289 | 12.50 | — | 0 | as written | line height 1.6 |
2 Lines
ISO 128 pens. Two weights do most of the work, 0.35 for what you see and 0.18 for what explains it; hidden lines sit between at 0.25, hatching below at 0.13. All lines are one colour, the ink. SVG strokes use the true width at 1 mm = 3.8 px. CSS borders (blocks and tables) are snapped to whole device pixels at 2x so the rules stay sharp; the snapped widths are in the fourth column.
| Pen mm | px at 96 dpi | px at 3.8 / mm | CSS border px | device px at 2x | Use |
|---|---|---|---|---|---|
| 0.13 | 0.49 | 0.49 | 0.5 | 1 | Hatching. Thread minor diameter (ISO 6410). |
| 0.18 | 0.68 | 0.68 | 0.5 | 1 | Dimension, extension and leader lines. Centre, phantom and cutting-plane chain. Balloons. |
| 0.25 | 0.94 | 0.95 | 1 | 2 | Hidden lines. Inner rules of the title block and tables. Lettering stroke at h 2.5. |
| 0.35 | 1.32 | 1.33 | 1.5 | 3 | Visible outlines and section outlines. Zone ticks. |
| 0.50 | 1.89 | 1.90 | 2 | 4 | Cutting-plane ends. Outline of the title block, revision block and tables. |
| 0.70 | 2.65 | 2.66 | 2.5 | 5 | Drawing frame (ISO 5457). Centring marks. |
- Unless otherwise specified
- DIMENSIONS IN MM [IN]
TOLERANCES: X.X ±0.25 X.XX ±0.13
ANGLES ±0.5° BREAK EDGES 0.25
DO NOT SCALE DRAWING - Drawn
- R. DIXON
- 2026-11-01
- Checked
- —
- —
- Approved
- —
- —
- Owner
- HULL/20
SPACEWAYS - Document type
- DRAWING STANDARD
- Status
- FOR APPROVAL
- Units
- MM
- Projection
- THIRD ANGLE
PROJECTION - Title
- DRAWING STYLE, HULL/20 DRAWING SET
- Size
- B
- Scale
- AS SHOWN
- Sheet
- 1 OF 3
- Dwg no.
- HULL-20-STD-001
- Rev
- A
3 Dimensions, terminators, hatching, balloons
Dimensions follow ASME Y14.5 unidirectional practice: text horizontal, h 2.5, centred in a break in the dimension line with 1 mm clear each side. Arrowheads are filled, 2.5 long, 3:1. Extension lines start 1.5 from the part and run 2 past the dimension line. The first dimension line sits 10 from the part, the next ones 7 apart. Leaders are straight and inclined, never horizontal or vertical, end in an arrow on an edge or a 1.2 dot inside a surface, and take a 4 mm shoulder before a note. Balloons carry the find number only.
Hatching
The materials and angles are the cad seat's convention, measured from its views. Adjacent parts take different angles. Fasteners, pins and shafts are not sectioned (ISO 128-40). Sections thinner than 1 mm are drawn as a double line, never filled.
| Material | Angle | Spacing mm | Pen mm |
|---|---|---|---|
| Aluminium, general | 45° | 2.0 | 0.13 |
| Stainless steel | 135° | 1.2 | 0.13 |
| Steel | 45° | 1.0 | 0.13 |
| Polycarbonate | 75° | 2.6 | 0.13 |
| EPDM, rubber | 45° / 135° | 0.8 | 0.13 |
4 Papers
Two colourways, one drawing. Vellum is graphite on cool drafting film and is the print colourway (pure black on white when printed). Blueprint is white line on Prussian blue. The page follows the reader's light or dark setting until they pick one. Paper tooth is fractal noise blended soft-light over the paper, never a gradient. Lettering must hold 4.5:1 against the paper at the grain's darkest and lightest point; construction colour holds 3:1 and never carries text.
| Token | Role | Vellum | Contrast | Blueprint | Contrast |
|---|---|---|---|---|---|
| --paper | the sheet | #E8EBE5 | — | #163F6A | — |
| --table | what the sheets lie on | #D3D8D1 | — | #0F3459 | — |
| --ink | all line work and lettering | #1F2427 | 13.0 | #EEF5FB | 9.8 |
| --ink-2 | web captions only, never on a drawing | #4A5258 | 6.6 | #B9D0E5 | 6.8 |
| --ink-3 | construction, never text | #767E81 | 3.4 | #7499BF | 3.6 |
| --red | revision letter and flags (redline) | #B0322A | 5.2 | #FFA38F | 5.6 |
Grain swing: the paper texture moves the paper's luminance by about ±3%. Ink on the darkest and lightest grain: vellum 12.0 to 14.0, blueprint 8.7 to 10.8.
VELLUM
BLUEPRINT
- Unless otherwise specified
- DIMENSIONS IN MM [IN]
TOLERANCES: X.X ±0.25 X.XX ±0.13
ANGLES ±0.5° BREAK EDGES 0.25
DO NOT SCALE DRAWING - Drawn
- R. DIXON
- 2026-11-01
- Checked
- —
- —
- Approved
- —
- —
- Owner
- HULL/20
SPACEWAYS - Document type
- DRAWING STANDARD
- Status
- FOR APPROVAL
- Units
- MM
- Projection
- THIRD ANGLE
PROJECTION - Title
- DRAWING STYLE, HULL/20 DRAWING SET
- Size
- B
- Scale
- AS SHOWN
- Sheet
- 2 OF 3
- Dwg no.
- HULL-20-STD-001
- Rev
- A
5 Sheet and blocks
Frame per ISO 5457: a 6 mm zone band with 8 columns and 6 rows (no I or O), characters h 2.5, ticks 0.35, frame 0.7, trimmed edge 0.25, centring marks 0.7 running 5 mm into the drawing space. Title block per ISO 7200 fields on a 5 mm module, 180 x 51, in the bottom right corner with its outer lines on the frame. Revision block per ASME Y14.35 in the top right corner, also on the frame: zone, rev, description, date, approved. Notes start "Unless otherwise specified"; a flag note carries its number in a triangle and the same triangle sits on the field. Parts lists per ASME Y14.34: find no., qty reqd, part or identifying no., nomenclature, material.
| Revisions | ||||
|---|---|---|---|---|
| Zone | Rev | Description | Date | Approved |
| ALL | A | FIRST ISSUE | 2026-10-31 | R. DIXON |
| B6 | B | NOTE 6: UV-PROTECTED SHEET | 2026-11-01 | R. DIXON |
Notes
Unless otherwise specified:
- Dimensions are in millimetres [inches].
- A flag note: the same numbered triangle sits on the field beside the feature.
| Find no. | Qty reqd | Part or identifying no. | Nomenclature or description | Material or specification |
|---|---|---|---|---|
| 1 | 4 | HULL-20-UFO-027-P01 | PANEL, TOP, LIFT SPOKE | POLYCARBONATE 3/16, UV |
| 9 | 40 | HULL-20-UFO-027-H01 | STANDOFF, GLASS, Ø.75 × 1.00 | STAINLESS |
View slots, and views from CAD
A view is any SVG in paper millimetres, placed at 100% so its scale is true. CAD output goes through drawings/import_view.py, which drops embedded style (the site's CSP blocks it), maps the layer groups to these classes, and sets the size at 1 mm = 3.8 px. The sheet's pens, dashes, lettering and colourway then win over whatever the exporter wrote.
| CAD layer <g id> | Class | Drawn as |
|---|---|---|
| visible, section | .cad .visible, .section | 0.35 continuous |
| hidden | .cad .hidden | 0.25 dashed 3 / 1 |
| center, cutplane | .cad .center, .cutplane | 0.18 chain 12 / 1.5 / 2.5 / 1.5 |
| cutend | .cad .cutend | 0.5 |
| hatch (data-material kept) | .cad .hatch | 0.13 |
| dims; arrow | .cad .dims; .ar | 0.18; filled |
| solidfill | .cad .solidfill | filled with ink |
| text, text.small, text.title | .cad text | osifont, h 2.5 / 1.8 / 3.5, caps |
| style="stroke-width:w" | .w13 ... .w70 | nearest ISO 128 pen |
6 What this matches
- NASA GSFC X-673-64-1F, Engineering Drawing Standards Manual (Goddard Space Flight Center, August 1994). PDF. Taken: the first sheet carries the complete title block, list of material, revision block and general notes; printed names in the approvals; the revision block in the upper right; the B to J format family.
- ASME Y14 series: Y14.1 sheet size and format, Y14.2 line conventions and lettering, Y14.5 dimensioning and tolerancing, Y14.34 parts lists, Y14.35 revisions. Taken: the anatomy and vocabulary of every block (tolerance block, find numbers, zone and rev columns), unidirectional dimensions, the leader and terminator rules.
- Swissmem Normen-Auszug, the "VSM-Büchlein" (2022 edition), the Swiss vocational extract of the ISO, EN and SN drawing standards. Swissmem. Taken: ISO 3098 type B lettering at h/10, ISO 128 pen discipline, the ISO 5457 frame with centring marks and the ISO 7200 title block; and the restraint of a Swiss shop drawing: one lettering weight, nothing ornamental, every mark carries information.
- Unless otherwise specified
- DIMENSIONS IN MM [IN]
TOLERANCES: X.X ±0.25 X.XX ±0.13
ANGLES ±0.5° BREAK EDGES 0.25
DO NOT SCALE DRAWING - Drawn
- R. DIXON
- 2026-11-01
- Checked
- —
- —
- Approved
- —
- —
- Owner
- HULL/20
SPACEWAYS - Document type
- DRAWING STANDARD
- Status
- FOR APPROVAL
- Units
- MM
- Projection
- THIRD ANGLE
PROJECTION - Title
- DRAWING STYLE, HULL/20 DRAWING SET
- Size
- B
- Scale
- AS SHOWN
- Sheet
- 3 OF 3
- Dwg no.
- HULL-20-STD-001
- Rev
- A