L x W x H units 1

[EcoMan]

This seems like the most logical forum to post this question. For a cube that measures 2 inches on each side, which one of the following is what you would write, assuming 8 in^3 isn't an option?
A. 2 in x 2 in x 2 in
B. 2 x 2 x 2 in
C. 2 x 2 x 2 in^3
D. (2 x 2 x 2) in^3

 

[ewh]

A, unless the units were already specified elsewhere, when I would choose none of the above and go with 2 x 2 x 2. That or 2^3 in.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[ctopher]

I agree with ewh.
C & D are redundant.

Chris
SolidWorks 11
ctopher's home
SolidWorks Legion

 

[CheckerHater]

If you create a drawing and units of measurement are clearly specified somewhere (titleblock), then A is good enough.
If it’s different document, say, catalog including both inch and metric items, then B.
Agree that C and D are too much. Also, as IN is unit of length and IN^3 is unit of volume; if you cannot say 8 IN^3, don’t say (2x2x2) IN^3, it’s just too confusing.

 

[drawoh]

EcoMan,

I tend to use your option B, unless my units are different...

25mm[×]1.5in[×]2'-4-1/2"

--
JHG

 

[DRWeig]

I'm not a GD&T fellow, but the tech style sheets for the scholarly journals (IEEE Journal, for example) would require your version A.





Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[EcoMan]

Thanks all for the feedback so far. My question is general, not just for drawings. Goober Dave, I don't see anything in the IEEE Editorial Style Manual (

http://www.ieee.org/documents/stylemanual.pdf)

that addresses this.

Besides which option is clear, I'm wondering which is correct. I don't think B is correct since L x W x H is a volume, but I seem to be outvoted. Let's see if others weigh in ...

 

[powerhound]

Well, you did ask how to specify a cube. That requires 3 dimensions. I don't see what calculating a volume has to do with anything. Per the ASME Y14.5 standard, when there is a space between the numbers and the "X", it indicates "by" as in 2 by 2 by 2. The units should be specified on the drawing somewhere so the use of "in" or "mm" would be moot, or redundant at the very least.

As far as I'm concerned being clear is correct. Being correct and unclear is not.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[EcoMan]

Not to get too philosophical, powerhound, but something can be clear yet incorrect. For example,
Clear and correct: (2 / 1) + 1 = 3
Clear and incorrect: (2 / 1) + 1 = 1
Unclear and correct: 2 / 1 + 1 = 3
Unclear and incorrect: 2 / 1 + 1 = 1

Everyone, let's forget about drawings and pretend the specification of a 2 x 2 x 2 volume appears, say, in the text of Y14.5 or in an abstract. I think that we can all agree option A is clear and correct but the longest. Disregarding clarity for the moment, which of B and C is technically correct and why not the other? I appreciate all replies.

 

[MintJulep]

A is the only correct option.

If a number has a unit then they belong together.

Consider a torque, say 250 pound -feet.

125 pounds x 2 feet.

B C or D make no sense at all if the units are different, so they make no sense if the units are the same.

 

[EcoMan]

Thanks, MintJulep, for your reasoning! That is a convincing argument for A being the only correct option. I see an Engineering Language/Grammar Skills forum where I suppose that I should've posted my original question.

 

[powerhound]

Your example misses my point...but whatever.

What are you really after EcoMan? In your OP it sounded like you were referring to a cube and how to specify it on a drawing. That is a relevant question for this forum and some have offered their opinion. Now, somehow volume is an important aspect of what you're asking about.

Y14.5 (Para. 1.5.3) says that units should be indicated on a print so if your print says "DIMENSIONS ARE IN INCHES" either in the note section or in the title block then 2 X 2 X 2 means "two inches by two inches by two inches." Plain and simple. On the other hand, if you are using both mm and inches on the print for some reason, then A is your only option.


John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[ewh]

B is incorrect because is forces an assumption that all numbers are of the same unit.
C is incorrect in that it can be interpreted as 2 x 2 x 8 (only the last digit gets cubed).

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[drawoh]

B is incorrect because is forces an assumption that all numbers are of the same unit.
...

C is incorrect

Why is B incorrect? The units should all be the same unless you are doing something weird like I was, above.

--
JHG

 

[powerhound]

If all the numbers are inside the parenthesis, then they are multiplied together first and then the product is cubed. So while C is not mathematically incorrect, it's not correct in the context of our discussion.

John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[ewh]

Yes, the units should be the same, but whether they are or not is still an assumption.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV