Need Help - Font Sizes/Sheet Sizes 1

[Madhu454]

Hi,
We use ISO standard in our companey for drawing creation.
The problem I see is we have same font size for all the sheet sizes (A0,A1,A2,... etc.,)
I think the font size has to be changed as per the sheet sizes.

Can anyone suggest me the font sizes that is preefered for various sheet sizes.
Is there any ISO standard for this? Can any one suggest me more on this?

 

[CheckerHater]

Try the following:

ISO 3098-0:1997 Technical product documentation -- Lettering -- Part 0: General requirements
ISO 3098-2:2000 Technical product documentation -- Lettering -- Part 2: Latin alphabet, numerals and marks

I am not sure if it has strict requirements for lettering heights.

ANSI/ASME Y14.2 Line Conventions and Lettering was updated in 2008, looks like it’s leaning towards same height for everything.

Also keep in mind that transition from manual drafting to CAD created its own unique requirements like letters being legible when drawing is printed on smaller piece of paper.

I think there is nothing wrong about having your own company rules that fit your needs.

Typical example could look like this:

 

[dgallup]

We use 2.5 mm for A3, 3.5 mm for A1 & A0. We allow either for A2 although I believe ISO recommends 3.5. The main criteria is legibility.



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[tmoxam]

Note sizes, title sizes, bom items should all be the same height from drawing to drawing.
The note on an A size is the same as the note on an E size sheet. However, if you are trying to print all of these onto the same size sheet of course you will have a problem.
One of our customers has a rule that all text be readable from a B size sheet. That means establishing a font on a D size ( the actual drawing size ) and checking to see that it is still readable on the B. Once the size is established the same standards are used on all drawings.

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[KENAT]

"I think the font size has to be changed as per the sheet sizes. "

Why?

Fundamentally the ASME lettering standard is built around the premise that drawings get run off full size - so a font size adequate at 1:1 is all that's required. I believe it gives 3mm as the minimum size from memory.

In practice we use .15" on all sheet sizes so that when scaled down to B it's still just about legible even from an E size. We do allow users of B size to shrink down to .12 if they really want but generally I'd suggest just to use C size if rather than go to that effort.

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[dgallup]

Well, ISO 3089 (1974) says the ratio of the square root of 2 in the range of heights for lettering (2.5 - 3.5 - 5 - 7 - 10 - 14 - 20) is derived from the standardized progression of paper sizes (A-series according to ISO/R 216). So obviously they intend larger letters for larger sheet sizes. I expect this came from the requirements of microfilming where every size drawing got shrunk to the same size negative, not too far from today's practice of printing everything to A/A4 paper.

Don't forget the OP specifically asked about ISO standards.

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[KENAT]

dgallup, I wasn't saying the OP was wrong just questioning why he thought that. Given the relevant iso std does in fact say so that effectively answers me.

I think the US letter sizes were also related to microfiche requirements but just set a simple minimum size. If I recall correctly there are larger size requirements for the title block and that I'm pretty sure was driven by microfiche.

Posting guidelines faq731-376

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(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[looslib]

We used 3.2mm (.125") on A-C size and 4mm (.156) on D-E size drawings. This was for dimensions and main notes.
Titleblock informations was in a different sise depending on the line was.


"Wildfires are dangerous, hard to control, and economically catastrophic."

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[CheckerHater]

More suggestions from couple different textbooks:

 

[drawoh]

"I think the font size has to be changed as per the sheet sizes. "

Why?
...

My old Machinery's Handbook (21st Edition) shows the scheme that looslib describes. At the time, it made sense. D[ ]and E[ ]sized drawings do not fit on work benches. They tend to get taped to walls some distance away, and they must be legible at that distance.

Today, you have to ask yourself what kind of printer you end user will have. Most of our D[ ]and E[ ]sized drawings are printed B[ ]size. 5/32" or 4mm lettering is completely readable from D[ ]size. 1/8" or 3mm lettering on an E[ ]size drawing is not legible when printed at B[ ]size.

--
JHG