Use of Tabular Dimensions

[cadboss]

Hello all,

I am in the process of assisting in the update of David A. Madsens' 5th Edition of "Engineering Drawing and Design", published by Thomson-Delmar Learning. I am working on Chapter 25 which covers HVAC, Pattern Development and Precision Sheet Metal Drafting.

In the Precision Sheet Metal Drafting section, it is stated that for items such as chassis layouts, that the method of dimensioning these parts "...includes standard unidirectinal, arrowless or tabular dimensioning systems".

My question is this: Is tabular dimensioning used that much for this type of sheet metal work?

Thank you for your reply's.

 

[drawoh]

cadboss,

Is there any reason it should not be?

JHG

 

[cadboss]

drawoh,

No, I just wanted to verify that it is used in sheet metal dimensioning. Tabular dimensioning isn't a style of dimensioning that is seen that much. My thinking was that ordinate dimensioning would be used predominantly but tabular does seem to have it's purpose in sheet metal.

 

[drawoh]

cadboss,

After nine years on SolidWorks, I finally used their tabular dimensioning. I recently had a plate with sixty threaded holes in it. Any dimensioning scheme other than tabular would have been unreadable. A complex, spline outline might be a candidate for tabular dimensions as per Fig.1.35 in ASME Y14.5-2009 (Fig.1.32 in ASME Y14.5M-1994).

Perhaps a better question to ask would be if anyone has an example of a justifiable tabular dimensioned drawing. It would illustrate the technique, and show off the problem it solves.

Tabular dimensioning is someting that sits in your toolbox until you need it.

JHG

 

[KENAT]

So are you talking about what around here is referred to has 'hole tables'? Or are you talking about extending this principle to other features.

Hole tables do get used some here.

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[cadboss]

Kenat, drawoh, both your reply's have answered the question well enough for me. The present statement in the book is "...the dimensioning and tolerancing for precision sheet metal parts are citical, and arrowless, dtum, and tabular dimensioning is often used with close tolerances to achieve an accurate layout". Based on your statements and relating them to the above text, tabular does have it's place and is used. Correct me if I'm wrong, but I would think a rewording of the text would be appropriate to cover both of your statements?

 

[drawoh]

cadboss,

I would be careful with the word "often". In my case, once in nine years probably does not qualify. KENAT's mileage may be different. Actually, I managed to do tabular dimensions on AutoCAD_10 a very long time ago.

I claim that the dimensioning and tolerancing of low precision components is critical too, and in many cases, more complicated and challenging. What you really need to do is show your readers what options are available for applying dimensions to their parts.

JHG

 

[cadboss]

drawoh, because of the use of the word "often" was the reason I was questioning. That's why I am thinking of rewriting it so it does offer it as a dimensioning option but not in such a manner that it would be used "often".

 

[KENAT]

I don't do a lot of complex sheet metal or even plate parts. However, when I do hole tables can be useful.

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