drafting methods 4

[palecactus]

is it okay to dimension section views.

 

[ewh]

Definitely, otherwise they would only be good for assembly drawings.

 

[aardvarkdw]

You shouldn't dimension in an isometric view because it doesn't show true size and shape and you can't dimension to a "hidden" feature. Cut views, section views, etc. are all okay as long as it is clear what the feature is that you are dimensioning (true size and shape).

 

[Heckler]

You can find everything you need to know about section views in Multi and Secional View Drawings ASME/ANSI Y14.3. It's a good buy. I'm currently redesigning a high speed miniture mechanism and was looking at the drawings. I found numerous mistakes: wrong projections, wrong callouts, dimensions to hidden lines and the granddaddy of them all a section view with hidden lines

Best Regards,

Heckler
Sr. Mechanical Engineer
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o
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Never argue with an idiot. They'll bring you down to their level and beat you with experience every time.

 

[ewh]

It depends on which standard you are refering to, and whether you are using board drawings or CAD drawings of solid models. ASME Y14.41-2003 definitely allows dimensioning to axonometric views (which are similar to iso views) on the drawing.

 

[ctopher]

Section views are OK to dim. I agree, do not dim to hidden lines.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[KENAT]

Palecactus

Yes!


Ok that's the short version.

I prefer sections to use of hidden line most of the time, I thought it was in a standard somewhere that sections etc are preferable but I couldn't find it last time I looked.

aardvarkdw,

I'm with you on ISO views but in my post the other day people seemed to think 14.41 might allow this.

Ken

 

[ewh]

Not only are sections preferable, but dimensioning to hidden lines is not a preferable method per Y14.5. Para "Dimensions should be shown in true profile and refer to visible outlines."

 

[ewh]

Omitted in my previous post: Para 1.4(c)

 

[wes616]

In some cases it is ok to dim to a "hidden" line, by drawing a broken out section, that makes the "hidden" line visible... but you should use this method discretely.

Wes C.
------------------------------
When they broke open molecules, they found they were only stuffed with atoms. But when they broke open atoms, they found them stuffed with explosions...

 

[ewh]

But then it is no longer hidden - That is a widely used method to get around hidden lines.

 

[palecactus]

IF ENOUGH INFO IS IN TWO VIEWS IN A DRAWING OF A PART, MUST YOU INCLUDE THE THIRD,(I:E TOP,FRONT,RIGHT)

 

[ewh]

No, if a view adds no information (callouts, dimensions, etc) you do not add it. Drawings are supposed to be a CONCISE definition of the part.

 

[ctopher]

You don't have to yell!
You only need another view if needed.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[ewh]

In fact, some items only require one view, such as a cylinder or sphere.

 

[palecactus]

sorry babout the caps

 

[ctopher]

I have a friend that used to teach drafting. He asked them to do a 3 view dwg of a ball bearing. Most of the class failed.

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-05)

 

[KENAT]

For a cylinder I usually put two views. People seem to miss the diameter symbol otherwise. Or do you know something I'm overlooking?

On the hidden in Y14.5, thanks ewh don't know why I couldn't find that the other day.

Ken

 

[ewh]

Your right that people may miss the diameter at first, but when they try to find the depth of the part, they usually see it.

 

[aardvarkdw]

Chris,
Was he requiring three views or just as many views as nessesary?

ewh,
I agree there are times when dimensions are allowable in iso or axo views as with ASME y14.41 but that I believe refers only to 3d models not to 2d drawings. I may be wrong on that, as I've mentioned in other threads I am still working on getting a copy of the y14 series here.