"S" in a circle. It's no longer needed?

[cadman1964]

I know the answer already i believe but i have some people here that doubt me, even knowing i have the ASME standard. According to ASME Y14.5M-1994 the "S" in a circle is no longer need, correct??. "S" use to mean "regardless of feature size"

I'm assuming the ASME didn't add this back in, correct???

Solid Edge V20

 

[SeasonLee]

Here are the figures of Standard Y14.5 1994 at page 216. Fig D-1 shows the former RFS symbol application, its a 1982 version.

SeasonLee

 

[CheckerRon]

Well, at the rocket shop I work at, we sre stuck with using the circle S on all our new program drawings (to 1994 standard) because we have both new programs and old sustaining programs to the 1982 standard, and engineering management does not want to confuse manufacturing with two systems---Rule 2A being the obvious justification.

When new programs come on board with 2009 as the contractural GD&T std, it will be interesting to see if they can deal with it.

 

[fcsuper]

CheckerRon, at least you'll have a good 5 years before Y14.5 gets updated again. I suspect the next revision will come quicker than the past two.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[cadman1964]

Here's something that made me shack my head. remember a few threads back i told how my boss threw away that drawing i markup to remove the "S". Well i open the drawing today cause i had to reference something and notice he had our detailer remove the "S"'s...... Funny...A

I guess he does listen to me once i awhile.....

Solid Edge V20

 

[fcsuper]

Or someone else that he respects told him to do it.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

 

[KENAT]

Maybe he found this thread;-)

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

 

[CheckerRon]

Perhaps fcsuper hit on it. Someone else also told him to take out the circle S's, or he knew you were right, but didn't want to admit it to you.
Just recently I told a designer to remove something from a drawing that was bad practice and he refused. Another good designer who was doing some part time checking saw the same drawing, made the same comment to him, and he changed it for that person.
So a full time checker's word is not valid, but a designer/part time checkers' word is? Makes me feel a little like Rodney Dangerfield.

 

[cadman1964]

Or maybe cause i ended up telling him that it's a alternative method allowed in the 1994 standard but removed in 2009. Any ways, least it removed and let's see if they follow this standard now....

Solid Edge V20

 

[powerhound]

As long as the "S" was applied to a TOP it is allowed as alternative practice. You can't use it on perpedicularity at all.

Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[CheckerRon]

Amen, powerhound. This is about Position only. It is the only place we still use the circle S.

 

[inpector]

The 'S' is no longer required - however it is implied. If there is no other symbol there to over-rule it the 'S' is really there anyway.

 

[CheckerRon]

inspector:
That was our original arguement. That is why it was dropped in the first place, but our engineering management isn't buying it.

 

[powerhound]

If your drawings are per the 1994 standard then there's nothing for engineering to buy into...they have to abide by the standard. If they want to change it then have them attend the next Y14.5 meeting.

Powerhound, GDTP T-0419
Production Manager
Inventor 2009
Mastercam X3
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[axym]

What do you guys think of the decision in '09 to disallow use of the explicit (S) symbol? I don't see the logic.

When training on the '94 version, I always recommend to students to put the (S) in the feature control frame even though it's an alternative practice. To me, the presence of the explicit symbol clearly shows that the designer really intended RFS as the condition. The "no modifier" implied condition leaves open the possibility that an (M) or (L) modifier was intended but accidentally omitted.

But now when I start training on the '09 version, I won't be able to recommend use of the explicit (S) because the practice has been outlawed.

Personally, I don't see the harm in giving the designer the option of using the explicit modifier instead of the implied condition. But there must be other reasons why the committee voted to remove that option. What do you guys think?

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

[cadman1964]

Me personally don't know the logic behind removing the "S". But, when i was trained i was told to leave it off. So now i just know if no "S" means RFS. Plus here, we are always pushing our customers to use "M" when ever possible. Easier for hard gaging on the floor

Solid Edge V20

 

[CheckerRon]

In 1973, MMC was the default modifier if no modifier was specified, and RFS had to be specified to apply (Rule 2A).
In 1982 this was modified to manadate the applicable modifier (MMC,RFS,LMC) for position and make RFS the default for other tolerances, dropping rule 2A to be more in-line with international practices.
Then in 1994, RFS became the default over MMC in a new rule (para. 2.8(a) to further be in-line with ISO and this is when circle S was removed. They kept the option, however, with 2.8(b)to satisfy those who would be confused and those that liked it (such as our friend Evan, and the management at my place).

So I see the total dropping of the circle S in the new 2009 standard as a further capitulation to ISO practices, which is OK, since it is an extension of rather than reversal of the current practice.

I don't agree with "belt + suspenders (braces)" approach that putting in the circle S tells everyone "Look, I really meant to do this. I didn't forget my circle M!

Follow the standard, agree nor not, for pity sake.