Dimensioning Using Unidirectional System 1
f. Oblique Sectional Views. Figure 66 on the following page illustrates a full-oblique sectional view, and figure 67 on the following page illustrates a halfoblique sectional view. Oblique sectional views are drawn in the same sectional views are drawn. Since the only difference between the two sectional views is the defining axis system, the information given in paragraph 2f, page 63, may also be applied to oblique sectional views.
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g. Planes. As the line projection theory was derived from the point projection theory, so the plane projection theory follows directly from the line projection theory. If we consider the following axiom To a draftsman, a plane is the area enclosed within a series of lines interconnected end to end. This differs from the geometric concept of planes in that it considers a plane a finite area, that is, an area with known boundaries. Figure 12 gives the front and top views of plane 1-2-3-4 and asks...
Figure Solution To Normal Surface Oblique Drawing Problem
Step 4. Erase all lines and smudges, check your work, and draw in all lines to their final color and configuration figure 59, view E . b. Inclined and Oblique Surfaces. Figure 60 on the following page is a sample problem that involves creating an oblique drawing from given orthographic views that contain an inclined surface. Unlike isometric drawings, angular dimensions may be directly transferred from the front orthographic view to the front oblique view, thereby eliminating the need for...
Figure Holetohole System
In the hole-to-hole system, all dimensions in the same plane are measured for the lines that define the critical holes. The baseline is not, in this case, a physical line, but is the center line between the critical holes. 8 Coordinate System. The coordinate system is a dimensioning system based on the mathematical x-y coordinate system. It is usually only used to dimension an object that contains a great many holes, for example, an electrical chassis. It is particularly well-suited to computer...
Figure Isometric Dimensions 1
e. Isometric Dimensions. Isometric drawings may be dimensioned by using either the aligned system or the unidirectional system. Regardless of the system used, the leader lines must be drawn in the same isometric plane as the surface they are defining. The guidelines for the dimensions in the aligned system are drawn parallel to the edge being defined, while the guidelines for the unidirectional system are always horizontal. Figure 53 on the previous page is another example of the unidirectional...
Figure Solution To Isometric Drawing Problem 1
b. Slanted and Oblique Surfaces. Figure 40 on the following page is a sample problem that involves the creation of an isometric drawing from given orthographic views that contain a slanted surface. The slanted surface is dimensioned by using an angular dimension. That presents a problem because angular dimensions cannot be directly transferred from orthographic views to isometric drawings.
Figure The Basic Reference System For Isometric Drawings
Normally, an isometric drawing is positioned so that the front, top, and right side views appear, as shown in figure 37 on the following page . This may be varied according to the position that the draftsman feels best shows the object. Dimensional values are transferable from orthographic views only to the axis, or lines parallel to the axis, of isometric drawings. Angles and inclined dimensional values are not directly transferable and require special supplementary layouts which will be...
Figure Showing The Bottom Edge Of A Hole In An Isometric Drawing
To determine exactly if and how much of the bottom edge of the hole should be drawn, locate the center point of the hole on the bottom surface and draw the hole by using the same procedure you used for the hole on the top surface. If the hole drawn on the bottom surface appears within the hole on the top surface, it should appear on the finished drawing. If the hole drawn on the bottom surface does not appear within the hole on the top surface, it should not appear on the finished drawing....
Figure Curved Line Projection Problem Solution
In the machine shop, the sketch or freehand drawing is a quick, accurate, and clear method of conveying ideas. Although sketching is not essential to the reading of a shop drawing, it is helpful in learning the language of mechanical drawings. Sketches are made rapidly and usually without the aid of drawing instruments, but they must be accurate and complete. Omissions and mistakes that would be discovered in making a scale drawing might easily be overlooked in a freehand sketch. Extreme care,...
Figure Constructing A Hexagon Fifth Method 1
Step 4. Draw in the hexagon figure 31, view C . e. Pentagon, figure 32 on the following page . In the following subparagraphs, we will discuss the procedures for constructing a pentagon. We have to draw a pentagon inscribed in a circle of diameter A. To draw this pentagon, perform the following steps Step 1. Construct a circle of diameter A. Step 2. Define points 0, 1, and 2 as shown in view A. Step 3. Bisect line 0-1 and define the midpoint as point 3 figure 32, view A . Step 4. Define point 4...
Figure Isometric Drawing Problem Containing A Slanted Surface
To transfer an angular dimensional view from an orthographic view to an isometric drawing, convert the angular dimensional value to its component linear value and transfer the component values directly to the axis of the isometric drawing. Figure 41 on the previous page illustrates this procedure by showing two angular dimensions that have, been converted to their respective linear values, then showing how these values are transferred to the isometric axis. Normally, a draftsman simply measures...
Figure Examples Of Angle And Hole Dimensioning
5 Dimensioning Small Distances and Small Angles. When dimensioning a small distance or a small angle, always keep the lettering at the normal height of either 1 8 or 3 16. The temptation is to squeeze the dimensions into the smaller space. This is unacceptable because crowded or cramped dimensions are difficult to read, especially on blueprints which are microfilmed. Figure 72 on the following page shows several different ways to dimension small distances or angles and still keep the...
Figure Solution To Oblique Drawing Problem With A Rounded Surface 1
e. Dimensioning an Oblique Drawing. Oblique drawings may be dimensioned by using either the unidirectional or aligned systems. The front views and all other surfaces parallel to it are dimensioned in the same way that they were in the orthographic views, but dimensions along the receding axis must be drawn in the same oblique plane as the surface they are defining. In the aligned system, guidelines for dimensions that define receding surfaces must be drawn parallel to the receding axis....
Figure The Reference System For Oblique Drawings
The receding lines may be drawn at any convenient angle. Upward and to the right at either 30 or 45 are most commonly used because these angles may be drawn with standard triangles. The choice of which receding angle to use depends on which angle best shows the object involved. Dimensional values are directly transferable from the front view of the orthographic drawing to the front view of the oblique drawing. Circles transfer as circles, not as ellipses as in isometric drawings, and angles...
Figure Drawing An Octagon 1
Step 1. Draw a circle of diameter D view A . Step 2. Construct four tangent lines as shown in view B. Step 3. Construct four lines, 45 to the horizontal, tangential to the circle as shown in view C. Step 4. Draw in the octagon view C . g. Approximate Ellipse, figure 34 . In this problem we have to draw an approximate ellipse from the following given information we have a major axis A-O-B and a minor axis of X-O-Y view A . To construct this ellipse, perform the following steps
General
This subcourse is designed to introduce the student to the principles of drafting and shop drawings. It describes the primary types of mechanical drawings used for shop drawings. It endeavors to teach the students how to read shop drawings through visual identification of lines, symbols, etc. Six credit hours are awarded for successful completion of this subcourse Lesson 1 DRAFTING AND SHOP DRAWING FUNDAMENTALS TASK 1 Describe orthographic projection theory and freehand drafting. TASK 2...
Cabinet Projection
Oblique drawings do not normally include hidden lines, although they may be used if special emphasis is required. a. Normal Surfaces. Figure 58 on the following page is a sample problem that involves creating an oblique drawing from given orthographic views. Since all surfaces in the problem are normal at 90 to each other , all dimensional values may be directly transferred from the orthographic views to the axis of the oblique drawing.
Figure Dimensioning An Irregular Curve
The table may also be used in reverse. If you know what your given design requirements are, look up these values in the table to find which part number you should call out on the drawing. 10 Irregularly Shaped Curves. To dimension an irregularly shaped curve, dimension the points that define the line. The more points you dimension, the more accurate will be your definition. Figure 77 on the previous page illustrates a dimensioned irregularly shaped curve. b. Tolerances. No dimension can be made...