I think “certain technical fields” refer to those that use pen plotters to print out (plot) drawings…
A pen plotter is like 3D printer with only a restricted z axis; it can only lift and lower a pen.
On line crossings or at the start of a line (e.g. extension line), when the plotter paused too long after lowering the pen, the amount of ink flowing from the pen could have been too much for the paper to keep it in place until it had dried. It was likely to get dots at such points.
To avoid dots where they don’t belong, gaps work fine.
But who really remembers the times of pen plotters? Since ink-jet and laser plotters took over, there’s no technical need for gaps on drawings anymore. It seems like a tradition some older people don’t want to give up. Gaps found their way into the standards and as they don’t do harm to anyone, there’s no pressure to remove them.
I only use gaps, when someone who pays for my work insists on having them. To me they are useless.
But in the end it is fine that we are now able to choose to use gaps or not.
With respect, that document is not really helpful here. It is called ‘Guide to British Standards’ it references only BS8888 in general.
The two Standards that FC uses (ISO and ASME) are documented in the Wiki and are both available (not necessarily strictly legally) to download as pdfs. So, if we do want to talk of FC’s Standard-compliance, we would be better to take our references from the horse’s mouth either by including a small extract of the Standard (see post above) or quoting a paragraph number from it.
Do you mean ?
BS 8888 2020, 5.2.5.3 Extension Line
… NOTE It is advisable to have a gap between the feature and the beginning of the extension line …
It is a relative long lived suggestion/convention as it can signifcantly improve the readability of the drawing
See Manual of Brtish Standards in ENGINEERING DRAWING AND DESIGN - BSI 1991 p90
…Projection Lines should start just clear of the outline of the feature and should extend a little beyond the dimension line…
BS8888 may not be ISO/ASME standard but is updated having taken into account
their documentation/documentation changes and is also used as a basis for other national standards.
See https://www.macleod.co.uk/resource-centre/bs-308-8888/
As such is a standard which should be supported (in this case by option) but is heavily based
around defining readable drawings
I want a little help on this topic. I have read this discussion topic and i am looking for a solution to place gap between dimension extension line and body. I saw your reply on fixing preference by link from git but i do not know how to use this link to install or copy the code to my freecad.
Preference should be fixed by git commit 5d93fbe0bb
