standard drawing scales 8

[KENAT]

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...

 

[wes616]

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

 

[drawoh]

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

 

[WHITMIREGT]

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.

 

[KENAT]

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...

 

[ewh]

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.

 

[looslib]

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

 

[ctopher]

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

 

[KENAT]

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...

 

[wes616]

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

 

[KENAT]

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...

 

[CheckerRon]

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.

 

[KENAT]

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...

 

[looslib]

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

 

[KENAT]

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

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

 

[fcsuper]

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

 

[ctopher]

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

 

[CheckerRon]

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.

 

[KENAT]

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...

 

[btrueblood]

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

Even my models of scale models?