"G" symbol on older print? 2

[legrand01]

We have a drawing here from the mid 80's that doesn't reference any standards. On the drawing is a symbol I haven't seen before. The symbol is the letter G inside a triangle and it is applied to a couple of dimensions. The best guess I have is that they mean that the feature the dimension applies to must be ground, but you'd think (or at least I would think) that the G would be applied to the feature, not the dimension. Also the part is made from 416 SS, Rc 26-32 so it wouldn't really need grinding and there's no surface finish requirements defined. There are no similar callouts on the drawing. I've attached a portion of the drawing for reference.

Any ideas on what this callout really is?

 

[legrand01]

Hmm... let me try the attachment again.

 

[CorBlimeyLimey]

That is a revision symbol. It references line G in the associated revision table.

 

[gmarken]

On more formal released drawings, a letter within a triangle indicates a revision change to that particular dimension.

 

[legrand01]

Thank you, that makes sense I guess since the rev on this print is up to J. It's just odd that there's no other similar letters on the print.

Thanks again!

 

[KENAT]

It's not that odd. If there is not drawing std defined, and different folks did different revs then they may have annotated it differently based on their previous experience/preferences.

Also, it may have just been an oversight, perhaps it should have been removed at rev H but got missed while all the other deltas were caught.

Posting guidelines faq731-376

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

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Alonzohawk]

Yup, revision symbol. It was standard with some companies to reduce drawing clutter by scrubbing rev symbols IF the revision was incorporated in a subsequent release. Others preferred leaving them as history, in addition to the ECN.

 

[ewh]

Also, rev symbols aren't limited to triangles; I am more used to seeing small balloons.

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

 

[MikeHalloran]

Did the .2502 hole used to be a .187 hole, or did you crop the feature referenced in the note near the center of the .375 R?



Mike Halloran
Pembroke Pines, FL, USA

 

[fcsuper]

The ASME revision std states that revisions symbols SHALL be circle with the revision letter (and if applicable, the number of the revision from a list). Other shapes are disallowed by default. I've already written the ASME board about this, since it seems rather silly to use circles in the first place (as they might get confused with balloons), and it seems silly to limit the symbol that can be used.

I don't recommend triangles, since triangles make good flag note symbols (allowed). Squares are OK flag note symbols, but are too similar to datum symbols for my tastes.

My personal preference is to use triangles for flag nots and hexagons for revision symbols. Hexagons are good candidates for revision symbols if you want to avoid them looking like something else.

Matt Lorono, CSWP
Product Definition Specialist, DS SolidWorks Corp
Personal sites:
Lorono's SolidWorks Resources & SolidWorks Legion

 

[dgallup]

There are old (obsolescent?) German triangular symbols for grinding although the ones I've seen do not have the G inside the triangle. I too vote for revision symbols, just wanted to share this ancient bit of trivia.

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