1. Technical Sketching and Shape Description

2. The Glass Box Method of Projection
If planes of projection are placed parallel to the principal faces of an object, they form a “glass box” as shown.
Notice that the observer is always on the outside looking in so that the object is seen through the planes of projection.
Since the glass box has six sides, six views of the object are obtained.
Conventional fillets, rounds, and runouts

3. The Glass Box Method of Projection
Since it is required to show the views of a three-dimensional object on a flat sheet of paper, it is necessary to unfold the planes so that they will all lie in the same plane.
All planes except the rear plane are hinged to the frontal plane, the rear plane being hinged to the side plane.
Each plane revolves outwardly from the original box position until it lies in the frontal plane.
Conventional fillets, rounds, and runouts

4. The Glass Box Method of Projection
Alignment of the six principal views
Conventional fillets, rounds, and runouts

5. The Glass Box Method of Projection
The Glass Box: Planes of Projection
Frontal plane of projection – the plane upon which the front view is projected.
Horizontal plane of projection – the plane upon which the top view is projected.
Profile plane of projection – the plane upon which the side view is projected.
Conventional fillets, rounds, and runouts

6. The Glass Box Method of Projection
The Glass Box: Fold Lines
Fold lines are imaginary lines separating the planes of projection corresponding to the hinged lines of the glass box.
Conventional fillets, rounds, and runouts

7. The Glass Box Method of Projection
Any one view of an object can only show two principal dimensions, the third dimension must be found in an adjacent view.
Conventional fillets, rounds, and runouts

8. The Glass Box Method of Projection
Transferring Depth Dimensions
A 45 degree miter-line is used to project the Depth dimension between the Top view and the Side view.
Conventional fillets, rounds, and runouts

9. Projection Box Drawing
Conventional fillets, rounds, and runouts

10. Projection Box Drawing
Conventional fillets, rounds, and runouts

11. Projection Box Drawing
Conventional fillets, rounds, and runouts