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standard drawing scales
8

standard drawing scales

standard drawing scales

(OP)
Quick and easy one (I hope) which ASME standard says to only use 1:2, 1:1, 2:1 etc.  I'm sure I've found it before but can't recal where.

I have a couple of prints with scales like 3:2 and one that seems to be about 1.25:1.  I think they've done this in part to cram it onto a B size sheet rather than use something larger.  At least one of the engineers in question is difficult to deal with so I want to make sure I'm on firm ground.

I'm not (I hope) just being pedantic but the drawings are pretty cramped and I want to use this as another factor to persuade them to use a larger sheet size.

Thanks,

Ken

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

Just a list of prefered scales. Nothing that says you shall not use a scale except for these. It does say that 1/1 should be used where possible.

Personally Will always draw on a sheet to big. I like the look of a small part on a big white background. But hey, that's art, not engineering

Wes C.
------------------------------
No trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.

RE: standard drawing scales

Kenat,

   My personal standard is whether or not I have a drafting scale that can measure that scale.   One of my metric scales does 1:125, so your 1.25:1 scale should work, assuming one of us got the numbers backward.

   None of my scales handle 3:2 as far as I can tell, so I would not do that.

   I strongly agree with 1:1 being the preferred scale.  

                     JHG

RE: standard drawing scales

Ken, Scales are discussed in ASME Y14.100-2004, para. 4.23. It states drawings shall be drawn to a scale that depicts all details of the item clearly and accurately, except diagrams, pictorials, cable assemblies and tabulations and other drawings not prepared to any scale where the word "NONE" is stated. It goes on to state that drawings should show an object or assembly to full scale. When full scale is not practicable, drawings may be prepared to reduced or enlarged scale.

RE: standard drawing scales

(OP)
Thanks all, I guess to some extent this was a case of my own prejudices that I'd picked up.  Maybe it was a UK thing, I can't remember.

I know I've been slapped for doing anything other than the 'standard' scales.

I'm all for 1:1 although a lot of the parts here are small and complex so 2:1 or more is very common/appropriate.

I also believe it's better to have a bigger sheet with lots of space than all crammed on a small sheet, to me it's not just art but a clearer drawing.

Just checked and the scale, at least on the hard copy I have, is about 1.21:1 (a 3.297 dimension is measured on the print at 4).

Anyway, probably wouldn't matter anyway as I've just been in a drawing where standards were pretty much thrown under the bus, I anticipate my lay off (as I'm a checker, no standards nothing to check to) sometime next week as part of lay-offs.

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

The only reference that I can find is in my Global Drawing Requirements Manual (for departments of defense and commerce), 1983.  It is based on DOD-D-1000, DOD-STD-100 and supporting documents, but things have changed in the last 24 years ;)
It states that the "preferred" scales are 1/1, 1/2, 1/4, 2/1, and 4/1.
As to which standard that was based on... ?
The only current reference that I could find is the one that Gary refers to, and it does not specify what scales to use.

RE: standard drawing scales

Not ASME, but I did find ISO5455, Technical drawings - Scales.

Full size: 1:1
Enlargment scales: 2:1, 5:1, 10:1, 20:1, 50:1
Reduction scales: 1:2, 1:5, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000, 1:2000, 1:5000, 1:10000

Larger or smaller scales should be in multiples of 10 based on this series.

Being an ISO standard, it should be for metric dimensioned prints only.


We had a corporate standard for inch dimensioned drawings of: 1:1, 1:2, 1:4, 1:8, 1:16, 1:32, etc.

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

Ben Loosli

RE: standard drawing scales

2
I have always followed looslib's scales shown.
The scale 3/1 has never been acceptable.

Chris
SolidWorks 07 4.0/PDMWorks 07
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog

RE: standard drawing scales

(OP)
Thanks looslib, we only invoke ASME standards but maybe I picked it up back in the UK.

That said at least some of my colleagues who've worked in more rigourous documentation environments do the same.

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

Often is the case where the computer automatically generates an odd scale like 3/2 due to the software, and people don't take the time to consider if it is good drawing practice. For instance, I will occasionally use a 1/15 scale and when cutting a detail view, Catia will automatically double the view scale to 2/15 scale. Most people will go ahead and adjust the scale to 1/8 or something, but some just leave it as is.

My guess is that may be going on with your designers. Maybe it's laziness, or maybe they just simply do not know, but with computer program... Garbage in = Garbage out & you must be smarter than the computer....

Wes C.
------------------------------
No trees were killed in the sending of this message, but a large number of electrons were terribly inconvenienced.

RE: standard drawing scales

(OP)
I don't think it's the case this time.  While the software does try to scale the view/s to fit the sheet, it usually selects from 'standard' scales.

I just checked and with ANSI (inch) formatting style selected my CAD gives 100:1, 80:1, 40:1 20:1, 10:1, 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:8, 1:10, 1:20, 1:40, 1:80, 1:100 as default options.

To get the scales they're getting I'm pretty sure you'd have to override the defaults.

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

The scale refs I know are the one Gary references, plus para 6.2 of ASME Y14.1, neither of which quote preferred scales anymore. I alway used the same ones EWH referenced in the Global DRM. I can't remember if the Genium DRM has a preferred scale table, but it is referenced as a source in your company DRM. If there was one, I would have used it. Gary W. should put one in the Genium for the users, to avoid those odd 1.25 or 1.33 to 1 scales that CAD jockies will use.

RE: standard drawing scales

(OP)
Good point Ron, I'll delve into the Genium manual in the morning.

I wont ask you to guess which department these drawings are from!

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

I deal with aircraft, so I see a lot of 3/320 scale on drawings!

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

Ben Loosli

RE: standard drawing scales

(OP)
You mean you don't have a 50ft-300ft long roll or paper drawn at 1:1winky smile

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

More time is spent trying to keep people using particular scales and is spent holding a scale up to a drawing (which is normally illegal anyway).  I was also taught to that doubles are preferred, but to use whichever scale is appropriate for each situation.  3:1 will make some cringe, but ultimately as long as the drawing fully communicates the drafter's intent, I do see how it matters, other than how effectively it makes someone cringe. :)  

Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group

RE: standard drawing scales

As long as the 3D model is 1/1 (or 1:1).
;)

Chris
SolidWorks 07 4.0/PDMWorks 07
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog

RE: standard drawing scales

The fact that the spec writers dropped preferred scale tables (that used to be in Mil specs) from the ASME spec tells us that in the Digital age of CAD, they don't think they are important anymore. Then why is there a scale required??? We old draftsman still want a sensible scale ratio, NOT  1.3345:1, .3345:1 or some other weird one.



Fossils are considered valuable, because there ain't many of them around anymore, and with their demise goes a lot of valuable information.

RE: standard drawing scales

(OP)
My main concern isn't so much that they are using weird scales, though I think it's bad practice, but that they are doing this to cram information onto a B size sheet rather than use a larger drawing.

I was hoping that requiring them to use standard scales would also push them to using a larger sheet size so everything isn't crammed in.

By crammed in I mean crammed in to the point it's difficult to interpret.

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

"As long as the 3D model is 1/1 (or 1:1).
;) "

Even my models of scale models? :)

RE: standard drawing scales

Camelot!
(It's only a model)
ssh!

RE: standard drawing scales

btrueblood and ctopher:

Who cares about your 1/1 model? It doesn't do much for a crammed up (or maybe I should use 2p's) B size draft file.

This is KENAT's problem and I know where he's coming from.

RE: standard drawing scales

The fun can really begin when they reduce those roll size drawings to 8.5" X 11" or 11" X Roll Length / Scale Factor. It makes reading Fun-duh-mental.

RE: standard drawing scales

"My main concern isn't so much that they are using weird scales, though I think it's bad practice, but that they are doing this to cram information onto a B size sheet rather than use a larger drawing."

Fine, so tell them so.  A cluttered print is a cluttered print, and adding sheets is not a no-no in your system, is it?  I tend to avoid huge sheet sizes, because many shops will print them or photocopy them to reduced sizes (A or B), and everything then becomes un-readable, regardless of how artistically I placed my views and callouts.

"Who cares about your 1/1 model? It doesn't do much for a crammed up (or maybe I should use 2p's) B size draft file."

See above.  A whacked-out scale may be just what is needed to make certain features stand out.  And if not, I put detail views on sheet #2, in whatever scale the CAD system says they are in, but re-lable the scale as "2X" or whatever.  Then I put a note on the drawing "DO NOT SCALE FROM PRINT".  And put "NONE" in the scale block.  Who cares, as long as the scale relationships between views is maintained.  I agree, a crapped-up drawing is a crapped up drawing, but the scale doesn't matter for that.  And if I ever catch some old fossil using a scale on my paper CAD drawing, with those notes above added, he and I will have a discussion.

RE: standard drawing scales

(OP)
btrue, we have some parts that are fairly complex.  To draw them on B or even C is virtually impractical.  They have so many dimensions that it becomes an incoherent mess.

If you try to do it on a B you end up with 2 or more of the same view, each on different sheets, to fit all the dimensions.  While occasionally unavoidable I think having the same view several times doesn't seem like good practice and going by some of the drawings I've seen it on it's almost always difficult to understand.  I've seen I think it was 5 or 6 sheet B size drawing that looked like a bowl of spaggeti or a spiders web, so many lines.  A colleague & I redrew it on E as I recall on a single sheet, that was a lot clearer.

I believe, and was taught, that fewer large sheets are preferabl to lots of small sheets.  If the machine shop can't handle the larger prints then they shouldn't accept the job.  However, to mitigate this we have our font size set to .15" rather than the minimum 3mm so it's pretty clear when reduced.

Anyway btrue, seems you'd side with them on this one, always useful to have the opposite view point.  They will talk about machine shops not having large plotters etc.

The reason I wanted the scale to back me up is that they don't care how bad their drawings look and will argue any changes I request so I like to have as much amunition and make sure I'm correct before I approach them.

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

I agree with btrueblood. The scale is not important, the data is. I require the lettering to be large enough when reduced to a "B" size, and change all colors to black when the drawing is released so that it is easy to read when reduced. Having more than one sheet to convey the engineering information is OK.

RE: standard drawing scales

I always use standard scales. I will start thinking about a B size dwg, if the views will not fit, I go to C size and so on. I will not use multiple sheets until I get to D size. This limits the amount of sheets to work with.

Chris
SolidWorks 07 4.0/PDMWorks 07
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog

RE: standard drawing scales

(OP)
So I accept that I was recalling incorrectly and none of the standards we explicitly invoke give scale preferences.

I have no arguement that more than one sheet is OK, however I think that one large sheet is better than multiple small sheets.

Glad I'm not the only one Ctopher, I was seriously starting to doubt myself.

When I said "how bad their drawings look" I meant as in regard to being difficult to read/incoherent/ambiguous.  I did not mean that every drawing should be so beautiful you can frame it and put it on your wall!

KENAT, probably the least qualified checker you'll ever meet...

RE: standard drawing scales

We tend to use larger format sizes for our drawings to keep them uncluttered and easy to understand.  That said, when they are released, they are printed to a B size (no facilities for drawing storage).  This is the official released document.  We send our vendors cgm's of the drawings, which can be plotted full size if they wish.  Since most of our products involve lofted bodies, the vendors are required to also reference the solid model.  The biggest problem we have come across with this system is signing off the drawings in those tiny boxes;)

As far as the scales we use, I have a very difficult time letting go of those that used to be "preferred", even though I realize that I don't really have a legimate reason for correcting drawings that use a "non-preferred" scale.

RE: standard drawing scales

As far as cramming parts onto inappropriately small drawings goes (in CAD), I simply never made an A size or B size drawing template at my company.  If some new-comer asks for those sizes, I simply say "C prints to A and D prints to B".  That usually settles it.  If more explanation is required, I say, "Since most printouts are to A size and B size, all the smaller size formats give you is less space on the drawing because more of it is occupied by the title block."  The advantage being that they have more room to detail their parts on a single sheet.  If part scale is an issue, it takes no more effort to set the drawing scale appropriately in one size over another since the CAD package we use sets the ideal scale automatically (and usually it's right) regardless of sheet size.

Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group

RE: standard drawing scales

Kenat,

A drawing that is ambiguous, difficult to read, or incoherent doesn't need any other argument from you.  I spend way too much time cleaning up older prints around here, and know what you mean.  I say again, there is nothing wrong with multipe representations of the same view, as long as you are careful not to "double dimension".  We have a lot of small parts with lots of goofy details, and getting all of the details called out from one view would crowd the drawing with arrow heads and leader lines.  When I do put details or aux. views on seperate sheets, I reference the new sheet on the view callout, and add a note such as "(FROM SHT. X)" on the view label.  Not a requirement, but helps the reader.

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