Small slips repeat from paper to paper. This lesson names six, shows the wrong and right version of each, and helps you build your own checklist.
It belongs to integrated drawing practice and draws on converting between stated scales and checking alignment across views.
What are the six recurring slips?
| Slip | Wrong | Right |
|---|---|---|
| Scale direction | 1:5 and a drawn 18 mm read as 3.6 mm | Drawn 18 × 5 = 90 mm real |
| Dimension figure on a scaled drawing | Drawn size written | Real size written |
| View position | Top view above the front view in first angle | Top view below the front view |
| Hidden detail | Solid lines for hidden edges | Dashed lines |
| Alignment | Feature at x = 35 in one view and 30 in another | Same x in both |
| Labelling | Views unnamed, scale not stated | Each view named, scale noted |
Worked example: catching a scale-and-dimension slip
An original bracket is drawn at 1:2. The drawn base is 45 mm long. The real length is 45 × 2 = 90 mm.
A student draws the 45 mm line and writes “45” on the dimension. The figure is wrong. The dimension must show the real size, so the correct figure is 90.
Test yourself with a second case. The real height is 64 mm. At 1:2, the line is 64 ÷ 2 = 32 mm long, and the dimension still reads 64.
Worked example: catching a view-position slip
The question says first angle projection, with the front view already drawn. A student places the top view above it because “top means up”.
In first angle projection, the top view goes below the front view and the view from the left goes to the right of it. Check the placement with a short rule: “first angle, top goes under”. If the question shows a projection symbol, read it before placing any view.
The mistake: fixing slips one at a time
A student notices a wrong dimension figure, fixes it, and moves on without checking the other five slips. The next paper brings a new slip from the list.
| Approach | Wrong | Right |
|---|---|---|
| After a slip | Fix that one | Log it, then scan all six |
| Next paper | Different slip appears | Checklist catches it |
The fix is an error log. After each practice, write the slip, the rule and a check, for example “Dimension: did I write real size, not drawn size?”
Check yourself
A part is drawn at 1:4. One line is drawn 22 mm long and another has the dimension 120. What real length does the first line represent, and how long should the second be drawn?
Answer
The first line is 22 × 4 = 88 mm real, so its dimension figure is 88. The second has real size 120 mm, so it is drawn 120 ÷ 4 = 30 mm long.
What to study next
Put everything together with completing an original mixed drawing practice set. For the labelling side, read checking labels and layout for a readable drawing.
If you want a teacher to help you build an error log from your own mistakes, see online one-to-one Engineering Drawing tuition.