【转帖】standard drawing scales

yang686526

standard drawing scales
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...
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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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
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.
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 re  
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.
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
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
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...
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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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...