INDUSTRIAL DRAWINGS & BLUEPRINT READING part 2

Part 1


What is an Engineering Scale?


We use an Engineer's Scale whenever dimensions are in feet and decimal parts of a foot, or when the scale ratio is a multiple of 10. So an Engineer's Scale has an inch broken into 10, 20, 30, 40, 50 and 60 gradations.


Why Specs Should be Read?


The most boring part of Construction Supervision may be reading Specs and General Conditions. So lots of folks just don't do it. They make that decision lightly, but the ramifications can be huge. Too many times Design Professionals hide little time-bombs in the Specs, or Special Conditions, that become important as the project progresses.
Perhaps it's a milestone in the schedule that must be achieved by a certain date. Or a requirement to never work before 8am in the morning or on weekends. Sometimes the project clean-up requirements can be quite different from what might make sense to you, but those are the rules for that project.
So at the start of a project, the Construction Supervisor should obtain his or her own copy of all the project documents and read them. After doing this on a couple of projects, you will learn what you can skim through and what needs more careful attention. Don't just blow off this duty, though.
The Project Specifications, General Conditions, Special Conditions and Construction Contracts constitute the rules for the project. It's easier to win the game when you know the rules.

Why aren't CAD Drawings all Done in 3D?


Blueprints traditionally got drawn as two dimensional (2D) drawings. Architects and Engineers drew in 2D because 3D was too complicated. When Computed Aided Design (CAD) became popular in the 1980s and 1990s, we assumed most drawings would now get drawn in 3D. But they don't. Things tend to change slowly in the design and construction industry. The typical set of plans produces today don't vary that much from plans produced generations ago. 
So why aren't most projects designed in 3D? I believe most Design Professionals are proficient at producing 2D drawings, but often don't understand the details of how contractors build buildings. As a young Design Professional working in a Design Office, I know I didn't.
So the complexity of producing 3D drawings carries the task of actually knowing how the project will be built. The level of understanding must be much higher for the draftsman. The technology works, but the learning curve for the Design Professionals is steep. On the other hand, many Owners try to limit their design costs and don't feel 3D drawings would add enough value to cover the cost of production of the documents.
The current state of affairs, then, has most projects being built on 2D drawings. The more complex projects, though, increasingly use 3D for architectural, structural, mechanical and electrical. Perhaps the main advantage of 3D is the crash feature. By modeling all the elements, the hundreds of crashes between beams, columns, ducts, pipes and the many other features in a building can be determined during design, then resolved in the office rather than in the field, with crews standing and waiting.

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