Game Design Ideas Measurements Metrics in Drafting
Metrics affects all aspects of drafting, from paper and pen sizes, to dimensioning practices.
This section is intended to give an overall understanding of modern metric practices when it comes to drafting.
Whether the drawings are the product of manual drafting techniques or CAD, the standards are still the same.
Contents
Metrics in Drafting
Paper Sizes Click here for information on metric and non-metric paper sizes. Drawing Sheet Layout Click here for information on standard drawing sheet layouts. Pen Sizes and Line Types Click here for information on metric pen sizes and line types. Scales Click here for information on the scales used under the metric system. Dimensioning Click here for information on how to correctly label dimensions on your drawings.
- From: Metrics in Drafting
Paper Sizes
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- Note: ADD Paper Sizes
The ISO 'A' Series
The ISO 'A' series of sheet sizes is based on a constant width to length ratio of 1:square root2.
The A0 size is defined as having an area of one square meter. This allows paper weights to be expressed in grams per square meter.
Each smaller sheet size is exactly half the area of the previous size. ie. If you cut an A0 sheet in half you get two A1 sheets; If you cut an A1 sheet in half you get two A2 sheets; and so on ...
This relationship of 1:square root2 is particularly important for reduction onto microfilm, or reduction and enlargement on photocopiers. All metric equipment including microfilm cameras, microfilm printers, photocopiers, and even drawing pen sizes, are designed around this ratio. This makes the process of archiving drawings, resizing, and modifying drawings easy.
Dimensions of Regular Sheets
Designation Dimensions A0 841 mm x 1189 mm A1 594 mm x 841 mm A2 420 mm x 594 mm A3 297 mm x 420 mm A4 210 mm x 297 mm A5 149 mm x 210 mm
Oversize Sheets
Oversize sheets are used when it is desirable to give extra protection to the drawing sheets by providing a binding or trimming margin.
Dimensions of Oversize Sheets
Designation Dimensions
RA0 860 mm x 1220 mm
RA1 610 mm x 860 mm
RA2 430 mm x 610 mm
RA3 305 mm x 430 mm
RA4 215 mm x 305 mm
RA5 153 mm x 215 mm
Rolls
The standard widths for rolls is 860 mm and 610 mm. The length of the drawing sheet can be cut as required to suit each individual drawing.
The ISO 'B' Series
The ISO 'B' series is defined to satisfy the requirements of drawing offices when the differences between the 'A' series sizes is too great.
In practice they are not commonly used.
Dimensions of Regular Sheets
Designation Dimensions
B0 1000 mm x 1414 mm
B1 707 mm x 1000 mm
B2 500 mm x 707 mm
B3 354 mm x 500 mm
B4 250 mm x 354 mm
B5 177 mm x 250 mm
Non-Metric Paper Sizes
For reference purposes the following table lists non-metric paper sizes still in use in some parts of the world.
Designation Dimensions (mm) Dimensions (in) US Engineering: ANSI A 215.9 mm x 279.4 mm 8.5" x 11" ANSI B 279.4 mm x 431.8 mm 11" x 17" ANSI C 431.8 mm x 558.8 mm 17" x 22" ANSI D 558.8 mm x 863.6 mm 22" x 34" ANSI E 863.6 mm x 1117.6 mm 34" x 44"
US Architectural: ARCH A 228.6 mm x 304.8 mm 9" X 12" ARCH B 304.8 mm x 457.2 mm 12" X 18" ARCH C 457.2 mm x 609.6 mm 18" X 24" ARCH D 609.6 mm x 914.4 mm 24" X 36" ARCH E 914.4 mm x 1219.2 mm 36" X 48"
Miscellaneous: Letter 215.9 mm x 279.4 mm 8.5" x 11" Legal 215.9 mm x 355.6 mm 8.5" x 14" US Government 203.2 mm x 279.4 mm 8" x 11" Statement 139.7 mm x 215.9 mm 5.5" x 8.5" Executive 184.2 mm x 266.7 mm 7.25" x 10.5" Folio 215.9 mm x 330.2 mm 8.5" x 13" Quarto 215.0 mm x 275.0 mm Tabloid 279.4 mm x 431.8 mm 11" x 17" Ledger 279.4 mm x 431.8 mm 11" x 17"
Drawing Sheet Layout
Standard layouts of drawing sheets are specified by the various standards organizations.
This is the layout of a typical sheet, showing the drawing frame, the microfilm camera alignment marks, a typical title block, parts list and revision table:
| File:Drawing Sheet Layout.gif |
Sheet Frames
It is standard practice for a drawing frame to be printed on each sheet, defining a margin around the outside of drawing area.
Drawing frames are standardized for each size of paper as per the following table:
Drawing Frames with No Filing Margin
Paper Size Border Width (mm) Dimensions of Drawing Frame (mm) Left & Right Top & Bottom Width Height A0 28 20 1133 801 A1 20 14 801 566 A2 14 10 566 400 A3 10 7 4003 283 A4 7 5 283 200
Title Block
The title block is normally placed in the bottom right of the drawing frame, and it should contain the following information:
- the name of the company or organization
- the title of the drawing
- the drawing number, which is generally a unique filing identifier
- the scale
- the angle of projection used, either first or third, generally shown symbolically
- the signature or initials of the draftsman, checker, approving officer, and issuing officer, with the respective dates
- other information as required
Material or Parts List
If the drawing contains a number of parts, or if it is an assembly drawing, a tabulated parts list is attached to the bottom right of the drawing frame, just above the title block.
The parts list should give the following information:
- the part number
- the part name
- the quantity required
- material specifications
- the drawing number of each individual part
- other applicable information
When the parts list is very large a separate drawing sheet may be used for the parts list alone.
Revision Table
A revision table is normally located in the upper right of the drawing frame, or at the bottom on the left side of the title block.
All modifications to the drawing should be documented here.
Zoning
A drawing may be divided up into a grid using letters and numbers. When zoning is used it is located inside the drawing frame.
Zoning allows easy references to various parts of the drawing by referencing a coordinate such as C7.
- Note: ADD Drawing Sheet Layout
Pen Sizes and Line Types
The ISO defines a set of standard metric line widths for drafting.
| File:Pensizes.gif |
Like the ISO A and B series sheet sizes, the pen sizes increase by a factor of . This allows additions and corrections to be made on the enlargements or reductions of drawings.
Each width is assigned a color code. The color code corresponds to that for the matching lettering stencil.
Line widths and color codes are standardized across all manufacturers.
Line Types
Letter Type of Line Line Thickness (mm) Application
A0 A1 A2
A3 A4 A Continuous - thick
0.7 0.5 0.35
Visible outlines
B Continuous - thin
0.35 0.25 0.18
Fictitious outlines Imaginary intersection of surfaces Dimension lines, projection lines, intersection lines and leaders Hatching Outlines of revolved sections Adjacent parts and tooling Fold and tangent bend lines Short centerlines
C Continuous - thin, freehand or ruled with zig-zag
0.35 0.25 0.18
Indication of repeated detail Break lines (other than on an axis)
D Dashed - medium
0.50 0.35 0.25
Hidden outlines
E Chain - thin
0.35 0.25 0.18
Centerlines Pitch lines Alternative position of moving part Path lines for indicating movement Features in front of a cutting plane Developed views Material to be removed
F Chain - thick at ends and at change of direction, thin elsewhere
0.7
0.35 0.5
0.25 0.35
0.18
Cutting planes
G Chain - thick
0.7 0.5 0.35
Indication of surfaces to meet special requirements
- Note: ADD Pen Sizes and Line Types
Scales
The scales recommended for use with the metric system are:
Actual Size:
- 1:1
Reduction:
- 1:2
- 1:2.5
- 1:5
- 1:10
Enlargement:
- 2:1
- 5:1
- 10:1
Decimal multiples of these base scales are also used. eg. 1:100, 1:250, 20:1
Indication of Scale
The scale should normally be noted in the title block of a drawing.
When more than one scale is used they should be shown close to the views to which they refer, and the title block should read 'scales as shown'.
If a drawing uses predominantly one scale it should be noted in the title block together with the wording 'or as shown'.
- Note: ADD Scales
Dimensioning
Dimensioning practices for metric drawings are similar to those for non-metric drawings, but there are some subtle differences.
This material outlines the current practices.
Dimension Lines and Projection Lines
Projection lines are used to indicate the extremities of a dimension. They are generally drawn up to 1 mm from the outline of the object.
Dimension lines are used to label a particular dimension. They have one or more arrowheads, which are typically 3 mm long x 1 mm wide.
Thin type B lines are used for both projection lines and dimension lines.
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Paper Sizes
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Page Background Image
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Further Paper Sizes
| Size | in × in | mm × mm | Aspect ratio |
|---|---|---|---|
| Letter | Template:Frac × 11 | 216 × 279 | 1.2941… |
| Legal | Template:Frac × 14 | 216 × 356 | 1.6470… |
| Tabloid | 11 × 17 | 279 × 432 | 1.Template:Overline |
| Ledger<ref name="PPD">Template:Cite webTemplate:Better source</ref> | 17 × 11 | 432 × 279 | 0.6470… |
| Junior Legal | 5 × 8 | 127 × 203 | 1.6 |
| Half Letter, Memo | Template:Frac × Template:Frac | 140 × 216 | 1.Template:Overline |
| Government Letter | 8 × Template:Frac | 203 × 267 | 1.3125 |
| Government Legal | Template:Frac × 13 | 216 × 330 | 1.5294… |
- See Paper Size
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Colour Text: Code: public class
| File:Do17 model.jpg |
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Notes
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