2b - The drawing surround (border) and title block is on layer FORM. The aspect ratio of the rectangular border has been chosen as 1.451 (33x22.75) as a compromise between the aspect ratio typically used with American A, B, C, D-size and European A4, A3, etc.. The title block proportion relative to the surround has been chosen to give sufficient space for the title block text without occupying too much drawing area.

2c - The template drawing 003s001 is sized to be a D-size drawing with inch units. To use this standard form for the full range of possible drawing job sizes, it will need to be scaled. The scaling should be by a standard factor such as 0.25x or 0.5x for smaller drawing limits or 2x, 4x, 8x, etc for larger drawings limits. When scaling the template drawing, the ENTIRE drawing form: drawing surround, title block, tolerance block, parts list and texts, should be scaled by the same amount to preserve the relative proportions of the drawing. The drawing surround and title block relative orientation should be maintained, i.e. no portrait orientation.

2d - The template drawing form includes a parts list, a tolerancing information block and various company logos. All these need not be included on every drawing and should only be used where appropriate. These are primarily intended for the detailed mechanical component drawings and assemblies. Additional standard tables and information blocks can be added as required for specific types of drawings, eg. architectural drawings. The revision block should be on every drawing. Additional lines in the tables should be added by copying the existing line spacing and font. Many possible company logos have been included on the template drawing, these can be delete and rearranged as appropriate for the originators of the drawings. If possible they should be left at the relative proportions and stacked above the title block as per the template drawing.

2e - The title block text CATEGORY, SUB-CATEGORY, ASSEMBLY, etc should correspond exactly to the same fields in the LBT CAN Numbering system database (001s002) and the naming and spelling should be standardized and strictly adhered to.

2e0 -Each entry in the title block is an AUTOCAD "attribute" which can be extracted for other uses. Use the DDATTE (or ATTEDIT) command to edit the attribute. Do not simply add text after each existing text, i.e. not "CATEGORY: TELESCOPE", etc.

2e1 - Note that only the CATEGORY and SUB-CATEGORY and ASSEMBLY titles are defined by the CAN specification. The other two levels of title below these are at the designers/drafters discretion but should be uniform and self-consistent for a particular group of drawings. It is not necessary to use all levels of titles, i.e. an assembly need not have SUB-ASSEMBLY nor PARTNAME. Unused titles should be deleted. Detailed part drawings should however include every level of title. The derivation of appropriate and consistent sub-assembly names is encouraged in any large assembly where it will assist in organizing part drawings.

2f - The title block spaces for DESIGN BY:, etc. should be filled in with the FIRST INITIAL and LAST NAME of the person except where it may be ambiguous, eg "J. Hill". The dates should use the AMERICAN convention of month, then day and then year.

2g - The CAN number is derived from the selected categories defined in the CAN numbering specification document (currently 001s002). It defines both the drawing's LBT drawing number and its file name. A space is provided for a local drawing file name which should be used to cross reference the LBT drawing with any internal drawing numbering system used by each of the LBT design offices.

2h - No fixed scaling wording should be used on the drawings. Instead scale bar symbols should be used. These can be inserted after scaling the template drawing form and should be selected with a dimension unit appropriate to the amount of scaling. The relative proportion of the scaling bar should be kept similar to the 0-3" bar shown as an example in 003s001. See below for more discussion of scaling and plotting.

2i - The view symbol (truncated cone) can be used to define the projection used on the drawing. Third angle projection is preferred but not essential.

3b - Maximum use is to be made of layers to separate drawing objects. New specialized layers and naming may be created in addition to the standard layers. This is encouraged however where possible and appropriate the standard layers should be used to enable uniformity with all LBT drawings. New layer names should be short but have some recognizable wording, i.e. avoid pure numbers. Some of the extra layers used in the Steward drawing office are given below.

3c - Standard layers:

Layer Name	Screen Color	Line Type	Comments
0	White (7)	Continuous	The main layer should be used to show the majority of the features of the drawing's subject.
CEN	Red (1)	Center	Shows centerlines and symmetry axes of components.
DIM	Yellow (2)	Continuous	For dimensions, both numerical and any written notes pertaining to dimensions or part features.
FORM	White (7)	Continuous	Contains the standard drawing border, title block and other features which will be used unedited.
HAT	Gray (8)	Continuous	Used for hatching (see additional comments below)
HID	Gray (9)	Hidden	Used for hidden features.
LOGO	Yellow (2)	Continuous	company logos
TXT	Cyan (4)	Continuous	text which is edited and any extended notes or comments.

3d - Suggested specialized layers:

Layer Name	Screen Color	Line Type
CON	Gray (8)	Continuous	(construction layer)
OPTICS	Cyan (4)	Continuous
RAYS	Green (3)	Continuous
SCREWS	Gray (8)	Continuous

4b - If possible all hatching should be blocked (i.e. not exploded). An appropriate hatching scaling and style should be chosen. The ANSI31 plain hatch pattern at 45 degrees is preferred.

4c - The hatching should be used only where appropriate. Avoid cluttering the drawing with unnecessary hatching and use it only where it is essential to distinguish part boundaries or show material types.

5b - Plotting should be considered only as a means of getting hardcopy of the drawing file. Specific drawing sheet scaling (making drawing units other than physical units) should not be used. An appropriate scaling bar will be included which can be used for approximate size calculations from the hardcopy.

5c - LBT has evolved the convention that all telescope and instrument components are drawn in units of millimeters; while the construction drawings of the enclosure of the telescope are drawn in inches.

6b - Within reason, the dimension style can be varied to suit the application and/or existing design office practices. The style preset in the template drawing form (003s001) is that used by Steward Observatory and is suggested as a suitable example.

7c - Associative dimensioning should not be used.

7b - Several font sizes can be used which appear appropriate in relative proportion to the drawing. These sizes should be standardized and selected as whole numbers. Avoid having too many font sizes. The relative sizes and number of font sizes shown in the template drawing form 003s001 should be taken as a guide. The smallest of these has been found to be readable with 600dpi laser hardcopy. The most common form of hardcopy is expected to be A-size (equivalent A4) laserprinter output.

7c - For B&W laserprinter plots, all colors should be assigned to the default Pen No. 1 and the pen widths set to the minimum value (in order to obtain the maximum resolution from the laserprinter) for all colors. The penwidth can be increased slightly (eg from 0.001" to 0.005") for specific colors such as the layer 0 white in order to highlight parts of the drawing. Note that the penwidths are user defined and do not stay with drawing files.

7d - For some bigger assembly drawings with large amounts of detail, or where colored pens would assist in understanding the drawing, or where working shop drawings are required, a pen plotter with larger format sheets such as D-size (equivalent A0 or A1) can be used for hardcopy. For pen plotters, the pen assignments should be to the matching pen color and with white (black) set to 0.7mm (0.028"). All other pen colors should be set to a width 0.35mm (0.014").

LBT has adopted a standardized filenaming system which uniquely identifies the electronic files and provides some degree of categorization based on the name. Each drawing or engineering document is given an eight character filename with:

• 1st - 3rd character: three digit number e.g. 026, corresponding to the category/assembly (CAN) number as per a derived reference list "001s002".
• 4th character: single letter identifying the project "site", i.e."s" for Steward,"a" for ADS, "e" for EIE, "m" for M3, etc.
• 5th - 7th character: three digit number 000-999, 1,000 possible drawings or documents numbered sequentially for that CAN number and for that project site.
• 8th character: single letter showing the revision sequence of the document. The first issue of the document should be "a", so all names have the same number of characters.
• File type designation: .dwg for Autocad drawing files, .dxf ASCII version of drawing files, .doc for Microsoft Word document files, etc.

9b - Where Autocad format drawings are impossible because they are sub-contractor or vendor's drawings then they should be standard ".dxf" compatible.

9c - The use of 3D should be limited to complex components or assembly drawings for which it is absolutely required..

9d - Drawings should be saved with the zoom window just outside the drawing boundary. Avoid creating large drawing entities outside the drawing boundary which stretch the drawing limits and make zoom extents an excessive size. It is helpful to save some standard views such as:
ALL - view zoomed to just outside of drawing boundary.
TIT - view zoomed to title block only.

Drawing Standards

Template Drawing Form

Doc_info_start
Title: LBT Drawing Standards	
Document Type: Reference
Source: Steward Observatory
Issued by: Peter Gray
Date of Issue: 05/17/95
Revised by: John Hill
Date of Revision: 06/02/97
Checked by:
Date of Check: 
Accepted by:
Date of Acceptance:
Released by:
Date of Release: 
File Type: HTML
Local Name: 001s006c.htm
Category: Overview - General
Sub-Category: Documentation
Assembly: Drawing Numbering              
Sub-Assembly: LBT Drawing Standards
Part Name: 
CAN designation: 001s006
Revision: C
Doc_info_end