standard containing rules for use of dash numbers in drawings

[tmoxam]

can anyone point me to the rules defining the proper (or permitted) use of dash numbers in part and assembly drawings. i learned the rules over serveral years at a defence contactor and now with a different customer there is a serious difference of opinion on the use of these types of numbers
i would appreciate a clue as to where to find the definitive standard for this.

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[Duwe6]

Sorry, but to the best of my knowledge and experience, there isn't one for the civilian side. Everybody makes up their own.

 

[tmoxam]

I had a read through DOD-100 which has a section based on ASME y14.24.
It states that dash numbers can be used for parts, assemblies, mono and multi-detail drawings. So i am not any better off than i was before.
My customer is asking for "kitchen-sink drawings" with the BOM being a large as it can be. They want everything that fits into the system assembly to be detailed on one 30-40 page drawing. Personally, i think that this is insane, but, we will have to live with the mess and the inevitable re-work. Since every drawing details it's own components there are common components that are named and stored in multiple files.
So instead of making a change to this common component on it's own drawing, we have to change a dozen or so 30-40 page drawings where this component is -004 of one assembly, -007 in another, and so on.
If there is no accepted standard, then does anyone have a list of COMMON SENSE rules for the use of dashes?

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[KENAT]

While there can be extenuating circumstances the customer sounds like a moron.

If working to ASME stds then ASME Y14-100 is the top level drawing spec. Y14.24 types and applications of engineering drawings may be of specific use, it has a reasonable amount of information on 'detail assembly drawings' etc. as well as discouraging them if I recall correctly!

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[KENAT]

Meant to say, you may want to ask in Drafting Standards, GD&T & Tolerance Analysis or even the config control forum though it isn't as busy as GD&T.

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[tmoxam]

thank Kenat,

i originally posted this issue on the GD&T forum ....and it was removed.
that's when i posted here.

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[IRstuff]

"does anyone have a list of COMMON SENSE rules for the use of dashes"

Common sense isn't that common, but nonetheless, everyone has a different system, so everyone has a different criterion, and no one wants to roll version numbers on every assembly when only one assembly is affected.

Philosophically, I don't see why you wouldn't wind up with different revs on different assemblies. Say assy A with part B gets rolled to A-1 because B was rolled to B-1 because an error relating to the functionality of A was discovered in B. Now assy C also has part B, but it maight not use the part of B that causes the error in A, so would anyone want the expense of rolling C when there is no functional benefit?


TTFN
faq731-376

 

[ewh]

Depending on what type of configuration control is in place, you may not need to concern yourself with revising assy C because of such a change to part B. As far as assy C is concerned, the new part B and the original part B are still interchangable (no change to form, fit or function relative to assy C).
Problems do often occur though when your file management procedures rely on part identification which includes revision in the identifying number.

Technically, the glass is always full.

 

[tmoxam]

just to be clear, irstuff and ewh
I am not speaking about revision or version levels of a part. this is about the part number. Particularly the dash number, often called a tabulation.
In a reasonable situation the dash numbered assys or parts are the same thing (but different). its the same cable, just various lengths. In a slghtly less reasonable situation these numbers may also be used within an assembly to describe various parts of that assembly. Perhaps in one assembly the base is XXXX-001, the sides are xxxx-002, the shelf is xxxx-003, etc. These are all shown in the same multi-sheet drawing.
My problem is that the system has 20 assemblies, each with a shelf, the same shelf, each with a different dash number, each within its own drawing. When someone makes a change to the shelf, there is alot of work to do. (x20)
So.....my rule of thumb has been"that you can make one (dash)part from the other", and that assemblies be as small as they can be.
What is yours??

Tim Moxam
Senior Mechanical Designer
Aversan Inc.
Toronto,Ontario,Canada

 

[KENAT]

14-100 and the 'associated lists' standard may have some info. It's been a while since I looked at it as between the ASME stds, our CAD system, our ERP system and our own internal doc control process we determined we couldn't' handle '-' numbers properly.

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[ewh]

Sorry Tim, I was addressing ITstuff's philosophical question.
As for your "rule of thumb", I agree; generally you can make one dash no. from another and it does only take two parts to create an assy. The problem is that the rule of thumb needs to be documented, and kitchen sinks get awfully cluttered. I would not enjoy having to meet your customers demands.

Technically, the glass is always full.

 

[IRstuff]

OK, but that's just (un)common sense. Why would anyone in their right mind call the same part different names without an external constraint?

As you point out, it becomes a logistical nightmare, since, usually, parts are marked with their drawing numbers, which increases inventory costs for no benefit. And the fact that they have spent the effort to give a part number to the part says that there is very little impact to using the same part number throughout. Unless, for some bizarre reason, they want to fluff up their IDL.

TTFN
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