Technical Drawing Standards: Leader Lines.
A leader line is a line that establishes a connection between a graphical representation of an item and some text. A leader points to a bit of our drawing and says:
‘Oi – Look Here’ and ‘Read This!’.
The leader line itself should be a continuous Thin line (see this post on Linetype Definitions). A leader line also has a terminator and some text. A leader line may have a reference line under the text.
The British technical drawing standards give us four different types of terminators to use with our leader lines.
An arrow terminator is used to point to an edge of an item. The dot is used to point to a face. The Architectural tick can be used for referring to multiple parallel edges. The final type of line has no terminator, and is used for pointing at dimension lines or lines of Symmetry.
Leader lines can have multiple segments and you can use one annotation to reference multiple faces and edges.
You can reference multiple parallel edges or faces with one leader.
It is recommended that you draw your leader lines at an angle to the rest of the drawing – i.e. Not parallel to the drawing itself. Increments of 15° are advised.
Finally, your Instruction text can be centred to the reference line, or it can sit above the reference line. The text should be a least twice the line thickness above the reference line. The text should never touch the reference line itself.
rules of placement of leader lines in drawing
Hi Rajat,
That’s a great idea – and one I will consider writing up in a future post :)
Paul
I’ve been looking for some documentation regarding arrowheads and callouts/leaders. When would it be appropriate to use and Integral symbol for an arrowhead? In the past my thought has been it could be used for something like a face/surface such as the use of the Dot but I haven’t been able to find documentation that would support or refute this idea. What are your thoughts?
Hi Benjamin,
I’m not aware of any use of the Integral type arrowhead in the British Standard, What do you use it to notate?
Paul
An integral arrowhead means “throughout” effectively. It’s useful for a keynote something like this: new flooring throughout – see finishes schedule.
Thanks for clarifying Dan,
I suspect that items such as flooring wouldn’t be covered in BS8888. Instead we would need to start with Pas 1192 which is that standard for Design documentation in construction.
Paul
Excellent distinctions. How about leader to revision clouds? I’m always torn between an arrow to specific issue or just a line to the cloud.
Hi Jack,
Revision clouds aren’t covered in BS8888. I’m guessing that they are more of an Architectural drafting convention?
Your convention ties into what I’ve seen on Architectural plan sets over the years.
Have I missed any?
Paul