CAD General Drawing Practice

In order to produce uniformity, especially where more than one person works on the same drawing or project, these standards should be adhered to whenever possible.  They should be deviated from only with careful consideration, good reason, and approval of the Project Manager.

Strive to make drawings attractive by reason of their neat, legible and uniform appearance.  To promote speed and legibility, keep drawings simple.  This applies to ?rough? or preliminary drawings as well as to final drawings.  Clutter and artistic displays are confusing and defeat the purpose of the drawings.

Although a major purpose of these standards is uniformity, much still depends upon the skill of the individual, the scale of the drawing and the purpose of the drawing.  When more than one person works on the drawing, or corrects another person?s work, make the drafting conform with that already on the sheet.

One purpose of a drawing is to convey an idea.  Engineering drawings are the graphical presentation of an engineering design.  The intent is to present the design of a project in a form that can be understood and constructed.  The user of the drawings depends upon it to understand the idea accurately.  Limit artistic display and aim for drawings that are uncluttered, easily readable and understandable.  Another purpose of a drawing, especially relating to CAD work, is the possibility of data retrieval and reuse.  If CAD drawings are built in a standard way, data can be extracted for use in other applications such as data bases, estimates, proposals and other drawings.  This is a major consideration when using CAD.   

The quality of the drawing is largely dependent upon the following criteria:

?                    Contrast existing features (lighter) with design features (darker) including text.

?                    Do not crowd the drawing.

?                    All dimension lines should be continuous.

?                    Produce a well proportioned drawing.

?                    All text, line work and leader lines with arrow heads and features are to be the same color as the layer it represents (see CAD layer control list).

?                    Give careful consideration to the placement of details and notes.

?                    Keep lettering size consistent.

?                    Be consistent within each job.

?                    Line, hatching and lettering legibility is to be maintained on full and half size prints.

The standard scale for construction drawings is given below: 

A large variety of materials and equipment will be used over a period of time, but the majority of CAD drawings will be done with the following:

All CAD drawings produced for the City of Lake Oswego shall be compatible with AutoCAD.  Consultants must submit AutoCAD drawings or .DXF files to the City as well as plotted, stamped, construction drawings.

Plotted on 15 lb. min. opaque bond at either (22" x 34") or (24" x 36") in size.

Plotted on 15 lb. min. opaque bond or 4 mil. double mat polyester film (22" x 34") or (24" x 36") in size.

As-Built Drawings

1. Plotted with permanent black ink on 3 or 4 mil. double matte polyester film or approved 20 lb. bond (22" x 34") or (24" x 36") in size.  Also include a compact disk of the final as-built drawings in AutoCad format will all X-references bound into each individual drawing.  Also, all layers must be appropriately selected (on, off, or frozen) for each 'individual' drawing (as visually depicted on the approved construction drawings).
2. Construction drawings are stamped and signed by Professional Engineers.  The signature is not an electronic part of the CAD drawing.  As the construction drawings are revised in CAD, the engineer's signature is not carried forward with the CAD drawing.  Revisions to construction plans must be approved by the project engineer and where possible re-stamped and re-signed.  The City will keep the stamped and signed construction drawings as well as an updated "as-built" copy.
   
3. Prior to the final inspection, the City will be supplied with full size 15 lb. min. opaque bond photo-copies of the proposed  as-built drawings.
   
4. Corrected as-built drawings shall be submitted within 30 days after the final inspection.
   
5. All design text that has changed from the original approved drawings due to construction, shall remain and be crossed-out with a single line through it.  The revised design text shall be located next to or near the original design text.
   

Any questions about the CAD Standards should be addressed to Kent Kirkpatrick, Engineering Technician at 503.699.7464 or email.