Drafting the center of gravity

[ingallspw]

Is there a "true" way to draft the calculated center of gravity? I've only seen it on one other print and I doubt the method I saw is a part of any ANSI spec (or equivalent).

On a side note...

Using NX6 (or NX whatever version), does anyone know of a way to automatically calculate the Mass, Inertia, and a Center of Gravity and add a call-out onto an assembly print that automatically updates each time the part is changed?

Thanks

Keegan

FYI...
The question about how to draft the CG came to mind after I asked the "Side note" question in another thread

http://www.eng-tips.com/viewthread.cfm?qid=253382&page=1

 

[KENAT]

Well, I don't recall seeing it in any ASME standard but, I used to work on stores where C of G went on quite a few drawings.

It was a circle with a cross hairs through it and two diagonally oposed quadrants shaded. Something like shown on sheet 2 of the below link.

http://www.virginiadot.org/business/resources/Cells-Symbols.pdf

The CAD question would be better asked in that forum, though ewh may be able to help you out. I know Solid Edge can do it.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[ewh]

I was about to post and thought I would check in the UG forum, and sure enough, the question was just asked there.

"Good to know you got shoes to wear when you find the floor." - [small]Robert Hunter[/small]

 

[TheTick]

Be sure to use reference dimensions to locate CG on print, unless you plan to actually measure and document it somehow.

 

[drawoh]

ingallspw,

There is an old baseball joke about someone asking about the bunt signal and being told that the coach will cup his hands around his mouth and scream "BUNT!"

Even if you do know what the symbol for CofG is, will anyone else? At some point, you have to type it out.

JHG

 

[MechEng2005]

I have also seen/used the symbol KENAT supplied. Although I typically leave the cross hairs off.

Drawoh also brought up a good point, that it really should be spelled out somewhere if you want others to be able to use it. Depending on the application, it may or may not be necessary. For example, if it appeared on a drawing for manufacturing counter-weights to get the CG where you wanted, it would probably be pretty clear what the symbol represented to anybody that needed to know.

-- MechEng2005

 

[ingallspw]

The only reason its going there is because customers keep requesting the values at random. If I put it on the masters we save the time of reopening the model, determining the properties, and emailing the results back to them.

I just don't want to make it look like a 9 year old put it on there with Crayons... I will at least use markers!!

The CG symbol looks like the way to go.

Thanks!

 

[ctopher]

In aerospace/military jobs I used to do, the CG was mandatory in the 3D models. It was acceptable to create a .jpg with a table shopwing the x,y coordinates based on a 0,0 point (usually the bottom-center of the part.
The customer drawing showed the CG as a point (cross-hair) with referenced x,y dims.

Chris
SolidWorks 09, CATIA V5
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