Technical drawing pen sizes
Technical drawing pens follow the same size-ratio principle as A series paper sizes, that is, an aspect ration of 1:√2, with the progression proceeding by folding the preceding size in two. When an A size piece of paper is folded in two it retains its proportions.
The standard sizes for technical drawings pens also differ by a factor √2, ie. 2.00 mm, 1.40 mm, 1.00 mm, 0.70 mm, 0.50 mm, 0.35 mm, 0.25 mm, 0.18 mm, 0.13 mm.
This means for example that after drawing with a 0.35 mm pen on A3 paper and reducing it to A4, you can continue with the 0.25 mm pen. (ISO 9175-1).
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
New planning rules to protect theatres, concert halls and music venues.
Public engagement in London Borough of Enfield's heritage strategy.
Reviewing the Roadmap to Recovery
Engineering services in the spotlight.
The Government's Summer 2020 economic update.
Britain's underground asset register
Getting organised below the surface.
Securing suitable water systems.
Love them or hate them, they are popping up everywhere.
The initiative to enhance the environment continues.
Could underused community spaces offer an alternative to working from home?
Keeping workers and workplaces safe in the United States.
A history lesson in geographic information systems.
A low tech, easy to use method of extinguishing small fires.