Machine Design
8 Common Drawing Mistakes to Avoid

8 Common Drawing Mistakes to Avoid

Drawing mistakes are part of the learning process. A number of CAD programs are now pushing for 3D model-based design drawings and installations, which will eliminate paper drawings and help reduce errors. However, the transition is slow and many legacy programs still require 2D drawing updates. Here are some common pitfalls to avoid in the 2D and 3D CAD world.​

1. Basic dimensions are useful when you are controlling the geometric tolerance of a part. Basic dimensions should always be to three decimal places and be boxed. Basic dimensions are used in conjunction with a geometric tolerance block.

2. Extension lines of dimensions should not touch the model sides. They should fall just short of the feature being dimensioned. Extension lines should also never be shortened.

3. A dimension line will not be used a dimension feature nor coincide with another dimension line.

4. Short dimensions should be placed close to the model and long dimensions should be farthest away. One should always avoid crossing dimension when possible.

5. Dimensions should line up in chain fashion. Do not create double dimensions unless you plan to make them reference dimensions.

6. Do not dimension to hidden lines as they cannot be inspected.

7. Always identify electrical ports and their clocking angles. This will help with installation.

8. Dimensions should not be placed in the area of the model, but always outside of the model.

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