Thursday, May 6, 2010

A CAD Standard

Here it is - it may not be perfect, but anything is better than nothing!
Unfortunately in the process of getting it here all the formatting is gone....but the info remains!

This procedure provides a basis for to produce drawings to NZS5901 (1987), ENGINEERING DRAWING PRACTICE IN NEW ZEALAND using AutoCAD.
This standard also lists the changes to the AutoCAD configuration, and forms a basis for layers, text styles and system variables as required.
All drawing numbers to have prefixes as follows:
P=PI & IDs
S=Process Flow Diagrams
Paper and Model Space
Place entities as follows:
Paper Space
Title Block at 1:1 Scale
Annotation Text/Dimensions for 3D Views
Parts Lists
Model Space
Object outlines
Annotation Text for 2D views
Sheet Sizes
Drawings to be on A1 Title Block, and usually this is printed on at A3. This means the 3mm high normal text comes out at 1.5mm printed.
All units in millimetres
Plotted Line Width
ALWAYS AN ENTITIES COLOUR SHOULD BE "BYLAYER". Hence whatever layer an entity is on controls its plotted line width
Plotted widths to be 0.05mm, 0.2mm, 0.45mm
The only exception is dimension lines, these are forced to white for the lines only.
Plotting and Scale of Entities
Plot scale is controlled by setting the zoom factor while in Model Space, for instance if the drawing is to be 1:5 scale, you would go to paper space, then enter Model Space by double clicking in a viewport, then type "ZOOM" "1/5xp". Then double click outside the viewport anywhere in paper space to get out of the viewport.
All entities to be drawn in Model Space to be full size, i.e. 1mm=1mm
These are set to an A1 sheet in the prototype drawing, and are up to the individual user to set, as they may prefer. Remember a grid will not show up unless limits are set to cover the area.
For Mechanical Drawings:
These are the layers normally to be used, and come already loaded on the prototype drawing.
Layer Colour Colour No Line type Pen Width (mm) For
0 white 7 continuous 0.05 Blocks written to file*
CL magenta 6 centerx2 0.05 Centrelines
DIM red 1 continuous 0.2 Dimensions
HID magenta 6 hiddenx2 0.05 Hidden Lines
HVY cyan 4 continuous 0.45 Heavy Lines
LGT white 7 continuous 0.05 Light Lines
MED yellow 2 continuous 0.2 Medium Lines
PH grey 253 phantomx2 0.2 Phantom lines
For Process and Instrumentation Diagrams (P&IDs):
Layer Colour Colour No
Valves yellow 2
Product red 1
CIP magenta 6
Equipment Major white 7
Equipment Minor grey 252
Instruments white 7
Instruments-Control white 7
Text white 7
Services-Gas light blue 140
Services-Chemicals Lt Green 83
Services-Liquids Dk Blue 145
Services-Compressed Air Lt purple 213
All linetypes are continuous for PIDs except for CIP, which is centerx2.
*NB When you write out a block to the library for other people to use,
put all of it on the 0 layer. In this instance you can make centrelines colour by name and
linetype not by layer. The advantage of this is that when someone brings it into a drawing, they
can put the block on a layer and it will show in that layer’s colours.
Plans and Elevations
These should always be in line with each other, ie if a vertical construction line is drawn through an item in the plan view, it should also go through the corresponding part on the elevation. This usually means that the view to the left of the plan view has the floorline running vertically up the page.
To make this view easier to work on just rotate your UCS by -90 degrees and issue the PLAN command. A lisp routine called RO90 will do this
The commands are UCS, Z, -90, enter, Plan, enter.
Entity Creation Modes

Entity Mode
Colour Bylayer
Dimension line colour White
Dimension extension line colour White
Dimension Text Colour Bylayer
Dimension style "Standard"
Linetype Bylayer
Textstyle Standard

Dimension Variables, and System Variables
1. Ltscale will initially be set at 4 for the prototype drawing so that dashed lines show up.
2. Mirrtext should be set to 1,because you would never want mirrored text.
3. Dimscale will be set to 1 so that if you are starting a drawing at 1:1 you will not need to reset it.
Note that contrary to a lot of common practice, the units are set to 3 decimal places; not zero places as many people set them. The logic in this is that when machined items need 3 decimal places you do not need to reset the units. For normal whole dimensions, ACAD conveniently suppresses the trailing zeros-see the dimzin variable.
A noted drawback of this is that when you are dimensioning a hole in the middle of a piece of 75 wide flat, the dimension will come up as 37.5, giving rise to a tolerance of +/- 0.1mm which is clearly not desired. The fix of course is to enter the dimension manually at the prompt.
Use standard Autocad ACAD.LIN
Heights and pen widths will be:
Entity Height Penwidth Colour
All normal text 3mm 0.3mm bylayer
Large text 4mm 0.5mm bylayer
Use Arial
Category Recommended Scale
Enlargement scales 50:1 20:1 10:1
5:1 2:1
Full Size 1:1
Reduction scales 1:2 1:2.5
1:5 1:10
1:20 1:25
1:50 1:100
1:200 1:500
Item References
Shall use numbers, not letters. The text height will be 5mm high .The circle to be 10mm diameter.
Block Library
These are kept at
Various categories are used in this folder eg bearings\saeco
If drawing say a motor, have a dimensioned drawing showing 3 views,
plus separate plan, side and end views with no dimensions on.
Be verbose with filenames, eg do not put "150kw motor", put for instance:
"Electric Motor-Teco-315s-85r.-plan - 2D"
Issue of Drawings
Only the project engineer may issue drawings. A document transmittal (standard form) must go with the drawings and a copy kept in the job file. All drawings must be stamped as to their purpose e.g., construction, for information, for tender etc. The project engineer is responsible to see the drawings are checked in respect to design and dimensioning, before issuing any drawings. The project engineer must sign all drawings issued. A copy of any drawing issued is to be kept on a stick file specific to the job, while the job is in progress. Finalised drawings should be stored in the drawing cabinets.
Sections and Views
On any drawing sheet sections and views start at A and work forwards through the alphabet
The following lisp routine sets up the layers for PIDs:
;Program written by Bill Le Couteur
;Auckland NZ
;Rev 0 date 18/8/97
;This program sets up layers
;the idea is that layer names are set ONLY
;by this routine...and this routine is run every time you open a drawing
;so if as a contractor you change employers, YOU ONLY
(defun c:laysetPID()
(setq the_layer (getvar "clayer"))
(setq layvalves "valves")
(setq layproduct "product")
(setq laycip "CIP")
(setq layequipmajor "Equipment Major")
(setq layequipminor "Equipment Minor")
(setq layinstruments "Instruments")
(setq layinstrumentscontrol "Instruments-Control")
(setq laytext "Text")
(setq layservicesgas "Services-Gas")
(setq layserviceschem "Services-Chemicals")
(setq layservicesliquids "Services-Liquids")
(setq layservicescair "Services-Compressed Air")
(command "-layer"
"m" layvalves "c" "33" layvalves
"m" layproduct "c" "1" layproduct
"m" laycip "c" "6" laycip
"m" layequipmajor "c" "7" layequipmajor
"m" layequipminor "c" "252" layequipminor
"m" layinstruments "c" "7" layinstruments
"m" layinstrumentscontrol "c" "7" layinstrumentscontrol
"m" laytext "c" "7" laytext
"m" layservicesgas "c" "130" layservicesgas
"m" layserviceschem "c" "111" layserviceschem
"m" layservicesliquids "c" "145" layservicesliquids
"m" layservicescair "c" "213" layservicescair
"m" "TEXT" "c" "120" "TEXT"
"s" the_layer "")
(command "-laYER" "t" "*" "")
(command "-laYER" "unlock" "defpoints" "")
(setvar "blipmode" 0)
(setvar "ltscale" 4)
(command "regenall")
(setvar "CMDECHO" 1)