Drawing conventions are the agreed rules for line types, dimensions, scale and labels. In SPM Engineering Drawing they decide whether a correct shape is also a correct drawing.
This page sits inside SPM Engineering Drawing. Use it to see how the lessons connect and where you should begin.
What does this cluster cover?
Four skills run through the cluster. You read what each line means, you read a size without measuring, you change between scales, and you label the sheet so a stranger can follow it.
The lessons follow that order:
- Interpret line types in an original technical drawing shows what outlines, hidden lines, centre lines and dimension lines each tell the reader.
- Read dimensions without measuring a distorted screen image teaches you to trust the printed size over the picture.
- Convert an original drawing between stated scales covers reduction and enlargement.
- Check labels and layout for a readable drawing brings the sheet together.
How do the parts connect?
Line types tell you what is there. Dimensions tell you how big it is, and scale tells you how the drawn size relates to the real size.
Labels then tell the reader which view, which scale and which part they are looking at. If one of the four is missing, the other three cannot rescue the drawing.
One small example to orient you
A plate is 60 mm long in real life and is drawn at scale 1:2. The drawn line is 30 mm, because the drawing is half the real size.
The dimension written on the drawing still says 60. A dimension always gives the real size, not the drawn length, and that is why the conventions matter: the line is 30 mm and the number is 60.
Where should you start?
If you are new to the subject, begin with line types and work down the list. If your lines are fine but your sizes go wrong, go straight to the scale lesson.
When you are ready to test yourself, use the conventions and scale practice set. Then move on to orthographic views, where these conventions are used on every view.
For a teacher to go through your own drawing questions, see online one-to-one Engineering Drawing tuition.