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1. Introduction
The purpose of this document is to provide guidelines on the design,
drafting and presentation of drawings associated with the Large
Binocular Telescope (LBT) project. Certain standards are outlined
which should be followed in order for LBT drawings to be easily
transferred from one design office to another and incorporated in
other LBT drawings. Other conventions are described which give the
project drawings a uniform, standardized format and a professional
appearance. However, where the adoption of these project-specific
standards are in conflict with local standard conventions and would
detract significantly from the efficiency of design and drafting, some
flexibility is permitted in the adoption of some of these LBT
standards.
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:
4. Hatching
4a - Any hatching must be put on a separate HAT layer so that it can be
switched off when not required. For drawings which have many complex
hatched areas, it is suggested to use several different hatch layers ie
HAT, HAT1, etc.5. Scaling & Units
5a - The drawing units can either represent millimeters or
inches. The main elements of the drawing should be scaled 1:1 in the
selected units. This allows measuring and checking dimensions in
Autocad. The selected units should be included in the title block
space provided by editing the attribute in the UNITS: box. The SCALE
attribute in the title block is intended to indicate the preferred
size of hardcopy paper, i.e. A,B,C,D,E or A4,A3,A2,A1,A0, not
scaled drawing units.6. Dimensioning
6a - All drawings should be dimensioned (have dimension labels)
so that scaling (measuring parts on the drawing) is not required.
However, we recognize that scaling is always required (see above).7. Fonts & Plotting
7a - Only the standard Autocad font "romans" should be used. No
other fonts are to be used - especially do not use non-standard add-on
font packages. Only the standard text style parameters should be
used, i.e. width 1.00 and oblique 0.0.8. CAN Document Numbering
This is a short summary of the LBT Project Drawing and Engineering Document
Numbering System. The full description may be found in document "001s001".
Filename Example: 270x002a.dwg - LBT shop drawing, for Circular Rail,
category/assembly number CAN 270, created by a vendor, drawing
sequence number 002, revision a. We have created a "special" site
code: "x" for vendor shop drawings and as-built drawings.