Dimensions of Regular Drawing Sheets
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Designation
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Dimensions
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A0
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841 mm x 1189 mm
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A1
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594 mm x 841 mm
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A2
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420 mm x 594 mm
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A3
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297 mm x 420 mm
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A4
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210 mm x 297 mm
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A5
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149 mm x 210 mm
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- The largest permissible size for a dimension is known as upper limit
- Plan section specification is necessary for making an estimate
- Representative fraction (RF) is defined as Length of an object in the drawing / Actual length of the object
- In an aligned system of dimensioning, the dimension may be read from Bottom or right hand edges.
- Comparative scale is a pair of scale having a common length of scale
- Hatching line are drawn at 45° to reference line
- Method of surveying considering Geometric survey.
Polar Co-ordinate system is mostly used in AutoCAD for Angular lines
Beam Compass - A beam compass is a compass with a beam and sliding sockets or cursors for drawing and dividing circles larger than those made by a regular pair of compasses.
A bow compass capable of drawing the smallest possible circles
- Drop Compass for Small Circles up to 29mm diameter
- Tube with Replacement Leads
- All Metal Quality German made Instrument
An angle can be set off and measured with the help of scale of chords
Diagonal scale is an engineering measuring instrument which is composed of a set of parallel straight lines which are obliquely crossed by another set of straight lines. Diagonal scales are used to measure small fractions of the unit of measurement.
- The sum of any two side of triangle is greater than the third side
- A right angle triangle revolving about its perpendicular side forming Cone solid
- sketch puts more focus on the face or front of an object
- sketches are usually drawn using a 45 degree angle to render the 3rd dimension
Isometric projection
- Sketches puts more focus on the edge of an object.
- sketches are drawn using a 30 degree angle
- In perspective drawings Plane of projection/ picture plane is placed between the observer and the object
- In an orthographic projection the rays are assumed to be parallel
Parallel perspective: linear perspective in which parallel lines of the object that are perpendicular to the drawing surface are represented as meeting at a point on the horizon in line with the common point of intersection of the lines of projection.
One-point perspective is also known as Parallel perspective.
Angular perspective:An object's vertical lines do not relate to the perspective rules of the horizontal lines. By changing the vanishing points of the object, one can make increase or decrease the size of the object.
Two point perspective is also known as Angular perspective.
AutoCAD Function Keys
| F1 | - | Help |
| F2 | - | Comment box |
| F3 | - | Osnap |
| F4 | - | 3DOsnap |
| F5 | - | Isoplane |
| F6 | - | Dynamic UCS |
| F7 | - | Grid |
| F8 | - | Ortho |
| F9 | - | Snap |
| F10 | - | Polar |
| F11 | - | Object Snap Tracking |