Rev A symbol on a Rev A print ?? 5

[evolDiesel]

Guys,

Hopefully this one will blow you away as much as it did me.

I have 2 individuals arguing over whether or not you show a Rev A symbol in the body of a Rev A print... to indicate what had changed, b/c in this example this new Rev A print was largely based on an old print. Is this making sense?

My take is that it is C-R-A-Z-Y to have any Rev A symbols. A Rev symbol is for indicating what changed going from the last Rev, and in the case of a "release-to-rev-A" situation... the print is brand new and has no history and if the engineer is trying to convey where the print came from, they should do that in the DCO, with reference documentation or a design journal, but it shouldn't be in the form of mysterious Rev symbols on a new print.

I mean seriously, have you ever seen a Rev A symbol??

We observe ASME Y14, and I've looked at 14.100, 14.3, and 14.35 and I can't find anything on this... which I think is an indication of how crazy this argument is... it's not even covered in the Y14.

Please chime in. Let me know if I'm the one who's crazy and of course BONUS POINTS if you can find where in Y14 it addresses a Rev A balloon.

Thanks,
Jack

Jack Lapham
Engineering Systems Administrator (E20)
Leupold & Stevens, Inc.

http://www.leupold.com

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Enterprise PDM 2010 sp

 

[swertel]

I have never seen any symbols on a drawing of initial release, whether it is released as X0, -, A, or any other identification.

--Scott

http://wertel.eng.pro

 

[ewh]

Good luck finding this exact situation addressed in the standards...
For what it's worth, I'm with you... if this is a new drawing and a new release, there is no revision to flag on the drawing. By definition, a new release is new. If a reference to a previous part/drawing is desired, the field of the new drawing is not the place for it, and a rev A notation there would be meaningless.

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

 

[KENAT]

First, lets make it clear that the initial release is not necessarily rev A per ASME.

While it's not directly relevant to the OP, it should be pointed out ASME Y14.35 (i think that's right) does allow for '-' or ' ' to be the initial release. In which case rev A would be a true rev, and so change indicators may be appropriate. See thread292-278425 for some details.

Also, it's not uncommon to use numeric revs or similar for pre-production or similar 'revisions' with the initial production release being rev A (or '-' or ' '). In these situations there is arguably a case for 'rev A' change indicator, though it wouldn't' be my choice.

However, getting back to the OP which is about initial release...

I've never seen symbols for true initial release. However, I have seen comments either in the ECO or the rev block explaining that the drawing was based on drawing xxx etc., or that it was previously proto rev 1 with no change, or similar.

In your case, I'd say it's probably best not to have it on the drawing and worry about indicating to manufacturing what changed from the old drawing on the ECO or similar.

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[Belanger]

I don't know if there is an ASME rule about this, but I do know of one large company that always has "Rev. 1" in the title block for the initial release of a new part.

If a revision is made, then the title block shows "Rev. 2." Strange...



John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[SteveMartin]

I think I can understand why one of your engineers might want 'rev A' callouts, but I agree with the posters above that they do not belong.

In a way this is unfortunate, because I've been involved with prints in similar situations where it would have been handy to have an easy way of saying 'like print XXXX, except with changes A, B, C...'. Indicating in supporting documentation is all well and good, but often that documentation gets stripped away from the drawing eventually. Mostly I'm thinking of time wasted reprogramming similar parts because the programmer never got the memo/documenation of 'similar to part 123 except...'.

 

[drawoh]

evolDiesel,

I think I understand what you co-workers are trying to do. I think the revision triangle is too weird to work.

They could always put a note on the drawing describing the differences between the old and the new drawings. This all is meaningless if you do not tell the user the number of the old drawing.

JHG

 

[ewh]

I agree with the note to indicate the previous part and any changes as a compromise solution. You could make it a flag note to locating where the changes are on the field of the drawing.

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

 

[SDETERS]

We have had some cases that we actually noted changes on a official drawing release. We have a dual number system. We send out the part to be quoted under a XC# then when the time comes to release this print for tooling or production we assign a different number to it. Now if something changes from the last change we sent to the customer and the production release we sometimes document the changes on the drawing. Also we have a place in out title block that calls out former XC# part number.

 

[evolDiesel]

I like drawoh's comment "This all is meaningless if you do not tell the user the number of the old drawing", which we don't do. I think it would be good to archive that information in the DCO, design journal, etc.

Thanks guys,
Jack

Jack Lapham
Engineering Systems Administrator (E20)
Leupold & Stevens, Inc.

http://www.leupold.com

Dell M6400 Covet
Intel Core 2 Duo T9800, 2.93GHz, 1066MHZ 6M L2 Cache
8.0GB, DDR3-1066 SDRAM, 2 DIMM
1GB nVIDIA Quadro FX 3700M (7.15.11.7950)
160GB Hard Drive 9.5MM 7200RPM FFS
W7x64 | sw-01: 55.92
SolidWorks 2010 x64 sp4.0
Enterprise PDM 2010 sp

 

[BiPolarMoment]

To give merit to KENAT's post, my current company uses '-' as the initial release and 'A' as the first revision (but we don't use revision change indicators).

I'm torn on revision indicators on drawings because on the one hand it quickly indicates to an outside manufacturer what dimension may have changed from the previous revision they have made before; on the other hand if you an indicator was accidentally omitted and your manufacturer doesn't notice you might get an out of spec part anyway.

Sure it's the job of the manufacturer to make it to print but that's not much solace when you have to send your whole lot back because of a stupid mistake and wait to get inventory that is needed for a product launch.

 

[evolDiesel]

BiPolarMoment is getting off on a tagent to this thread, however.. I can't tell you how many times that issue comes up at my company. We struggle with change order efficiency meanwhile... there's a lot of calculated risk if [as a machine programmer] you assume that ONLY what was documented on the print is what actually changed in the design. Most Design Engineers are more worried about design than documentation. Nature of the beast, right?

Jack Lapham
Engineering Systems Administrator (E20)
Leupold & Stevens, Inc.

http://www.leupold.com

Dell M6400 Covet
Intel Core 2 Duo T9800, 2.93GHz, 1066MHZ 6M L2 Cache
8.0GB, DDR3-1066 SDRAM, 2 DIMM
1GB nVIDIA Quadro FX 3700M (8.17.12.5896)
160GB Hard Drive 9.5MM 7200RPM FFS
W7x64 | sw-01: 55.92
SolidWorks 2010 x64 sp4.0
Enterprise PDM 2010 sp

 

[KENAT]

Well, the trouble is, if you concentrate on documentation you get accused of not really being an engineer;-).

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[ctopher]

If you don't have a person to handle document control, or configuration management, or have all engineers trained in either/both, there will be eventually problems and headaches.
ASME standards need to be followed and in house standards to be written then followed. Whatever revision scheme is selected, the company needs to be educated in it.
Vendors need to be aware of them.
It's when everyone in the company 'thinks' what he/she is doing in the correct way is when others get confused.
And parts are made wrong my the machine shop or vendor because of inconsistencies.
Setup standards and a plan, stick to it. Every once in a while you will come across someone that's capable of being educated.

Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion

 

[dgallup]

We use numeric revision levels (1, 2, 3 ...) but we never put revision 1 change symbols on the drawing. We do have a field for "similar to" or "supersedes" to reference older drawings. Usually the manufacturing engineer will come to me to ask what the differences are.

If we put the level 1 change symbols on the drawing we would also have to create an alteration record which would have to refer to the other drawing. More trouble than it's worth in MHO.

 

[TJOrlowski]

I'm with the OP. If I saw a shop drawing with no changes from it's initial release that had mysterious revision marks, and it was made by one of our engineers, I'm sure their explanation would be too crazy for me to care to listen to it.

-TJ Orlowski

 

[fcsuper]

Arguing about this doesn't seem like a value-added activity. The irony is that the argument itself is about something that is not value-adding either.

Here's the possible argument:

"The revision symbol may be used to identify an item or area of change on the drawing." ASME Y14.35 paragraph 5.4. How can their be a change on the drawing if the drawing is new? Rhetorical question. That should end the conversation.

However, if it doesn't, ask for justification of why there should be an exception to the standard. To this, the antagonist may say, "Where does the standard say we cannot use revision symbols on new drawings." To this you can say, "the ASME gives us rules and processes to follow; not to not follow." The antagonist will then look up the word "not" in the standards and find that it is indeed used at some point.

As this point, the argument gets estoteric and has nothing to do with the topic at hand. With no resolution, the whole thing is just silly. Compromise is necessary.

The symbols can be used in a way not specified by the standard if their non-standard use is defined on the drawing. Add a note to the drawing that says why they are there and what they are showing in relation to the old drawing (which should be mentioned by "name").



Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[MechEng2005]

While I'm not familiar with the standards, so this is just my gut feeling on the matter. I think that it is acceptable to have the initial release for fabrication to be rev. A, B, E, 7, 1892, or whatever. However, where I work "document control" requires only a paperweight.

The fabricator is required to produce the part on the print. It shouldn't matter to them what revision it is. Perhaps I am designing a custom stool, and the customer has changed their mind 8 times about how tall it should be. So I keep changing the length of the legs and sending it back for their approval before I start fabrication. I don't see a problem with using revisions to keep note of these changes. When I finally get the customers approval and release the drawing for fabrication, why should I need to "reset" the revision level?


-- MechEng2005

 

[KENAT]

In some places it's to do with the level of control the print is under. In early stages config control may be pretty loose. At some point, often when going to initial production, the control is formalized.

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