First angle vs third angle
| First angle | Third angle | |
|---|---|---|
| Object placed | In the first quadrant, in front of the VP and above the HP | In the third quadrant, behind the VP and below the HP |
| Top view | Below the front view | Above the front view |
| Left side view | On the right of the front view | On the left of the front view |
| Used in | India, Europe (IS, ISO) | USA, Canada |
Steps for orthographic views
- Choose the front view direction that shows the most detail
- Draw the front view with overall width and height
- Project the top view below (first angle) using vertical projectors
- Project the side view using a 45° line or projectors
- Add hidden lines, centre lines and dimensions
Isometric drawing vs isometric projection
- Isometric drawing: true lengths along the axes; quicker and common in exams
- Isometric projection: lengths reduced by the isometric scale (about 0.816 or 9/11)
- Axes at 30° to the horizontal on both sides plus one vertical
- Circles become ellipses, drawn by the four-centre method
FAQs
Why is first angle projection used in India?
Indian standards (IS / SP 46) follow first angle projection, as in most of Europe, so drawings are read the same way across industries.
What is the isometric scale?
It reduces true lengths to about 81.6% (√2/√3) so the isometric projection looks correct; isometric drawings skip this and use true lengths.
Which is easier in exams?
Isometric drawing with true lengths is usually faster; orthographic questions test projection rules and are worth practising thoroughly.
Where can I see a full sheet list?
See <a href="/engineering-drawing-sheets">engineering drawing sheets for first year</a>.
Last reviewed: 2026-11-07. Always follow the format your own department gives you.