Drawing within a drawing - revisited 1

[Careful]

thread1103-316521

The linked thread was the most definitive I could find on this subject, but I'm looking for more information, and opinions.

In your opinion is the practice of drawing within drawing as shown in the attachment acceptable (I know the object shown isn't fully dimensioned)? If so, what units would the object be measured in, and what tolerance would be applied?

Also does anyone know of a reference book that describes the proper procedure for this practice? (ASME Y14.24? I don't have it, but if this practice is covered, I'll get it)

Thanks!

 

[KENAT]

Not sure that drawing within a drawing as such would be covered by any ASME standard.

However, ASME Y14.100 does have a little bit on Drawing Identification & Ownership in section 6.5 & figure 1 & reference to 14.35 where I think the relevant paragraph is 6.2.

The above only adds the 'new' company's information in a block above the title block.

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[drawoh]

Careful,

Either your information is clear and correctly formatted, or it is not. The use of the PDF file is irrelevant. You have the following problems.

[ol]
[li]The PDF image may be subject to copyright, or some other conditions noted on the vendor's drawing. You may be violating these.[/li]
[li]If you are running 3D[ ]CAD, the PDF[ ]drawing is not driven by your 3D[ ]model. Your 3D[ ]model could be seriously in disagreement with your drawing.[/li]
[li]Dan Hunter's objections as noted in the linked thread.[/li]
[/ol]

--
JHG

 

[Careful]

drawoh,

My question wasn't in regards to PDFs, and copywright. Only which tolerance block people feel should be applied to the object, and if anyone had references regarding use of drawings within drawings, but thanks for your input.

 

[MikeHalloran]

So, ABC Company wants to buy a part just like the part that XYZ company makes,
except the default tolerance on 2 digit dimensions 0...99mm
is not +/- 3 mm,
but +/- 2 inches ?

OR do you want a part that's 25.4 times larger?

What your drawing seems to say is that you want a part that looks like XYZ's rectangle of 15 mm +/- 3mm length,
except you want a rectangle that's 15 inches +/- 2 inches long.

I think you have illuminated yet another way that using someone else's drawing within your drawing can go wrong; your buyers and your inspectors will be calling you all the time, and your boss's boss will be yelling at you for specifying the wrong goddamn parts, again, every time you get a new buyer or a new inspector.

Don't expect to have a long career there.






Mike Halloran
Pembroke Pines, FL, USA

 

[Careful]

Mike,

I inherited this system so I’m not worried about my position, but thanks for your concern.

The way I interpret the tolerancing is, as ABC company’s block clearly state “UNLESS OTHERWISE SPECIFIED” as the first line, that you would apply ABC’s block tolerance to anything within it’s drawing border, unless there is an superseding tolerance applied to any object, which XYZ company’s tolerance block does to items within its border. So the piece would be 15 mm +/- 3mm.

If, for some reason, an additional object was shown in ABC company’s drawing along with, but outside of, XYZ company’s border, then the ABC company’s block would apply and the units of that item would be in inches.

Yes/No ?

 

[swertel]

I highly recommend against a drawing within a drawing. Too many ways for it to go bad. Here are some possible solutions in random listing.

Vendor Item Drawing
Source Control Drawing
Modified (Vendor Item) Drawing
Recreate the drawing to your standards and define the original design authority per KENAT's suggestion.

Regardless of which way you do this, you are assigning your own internal part number and cross-referencing the vendor's part number.

--Scott
www.wertel.pro

 

[MikeHalloran]

Two sets of default tolerances on the same sheet is just asking for trouble.
"EXCEPT AS NOTED" specifically refers to a NOTE, which is not present.
There is no note saying that ABC tolerances do or do not apply within the outline of its drawing. The 'inner' tolerance block is not identified as a NOTE, so the 'outer' tolerance block applies. ... or does it?
AFAIK there is no standard for how to interpret general/default tolerances in multiple zones of a drawing.


Also, given the usual very fine print in title blocks, you do not have the right to reproduce and distribute XYZ's drawing without their written consent. It's probably visible on some of your photoreproduced originals, so you don't have a leg to stand on in court. If their title block includes their copyrighted logo, you are screwed even if they forgot the reproduce and distribute note.

What do you do when XYZ changes their part to a circle?

I've never seen such an extremely bad example in practice, but it's a bad practice regardless.

What I have seen, is source control drawings, that may include photos or simplified drawings of a purchased part, with just enough text or dimensions to assure that what was received is the desired part, but never including a vendor's tolerance block, and rarely their title block.

I have also seen attempts to use vendor part numbers as one's own, and that worked out badly too, because 'our' computer could not accept all characters used in others' part numbers, and our clerks used different tactics to deal with special characters, so a search on the vendor part number would fail, but a search on the title would succeed, except for misspellings.


The problem is not how >>>I<<< interpret your drawing, it's how every fabricator, buyer, and inspector along the way, for every production lot, interprets it.






Mike Halloran
Pembroke Pines, FL, USA

 

[drawoh]

drawoh,

My question wasn't in regards to PDFs, and copywright. Only which tolerance block people feel should be applied to the object, and if anyone had references regarding use of drawings within drawings, but thanks for your input.

Who is fabricating this part? If it is your vendor, he is working to his tolerances, and probably he is unaware of your drawing. Keep your tolerance block off the drawing, or at least, make it clear the vendors tolerances have precedence over yours.

If you are fabricating the part, I strongly recommend modelling in 3D and using your own drawings. The tolerance issue is resolved.



--
JHG

 

[dgallup]

The only time we do a drawing within a drawing is to add our part number. That is the ONLY thing we specify, everything else is the suppliers drawing.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[swertel]

If all you are doing is adding your part number, then you should be using a Vendor Item drawing or a Source Control drawing. In either case, you recreate their geometry and only put as much information on the face of the drawing that you want to inspect to ensure a compliant part (you got what you asked for).

--Scott
www.wertel.pro

 

[dgallup]

There is no value in recreating their geometry. There is a possibility of introducing an error. The proper thing is to just stick their drawing inside a bigger drawing border with our part number thank you very much.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[swertel]

1) Either you downloaded their model and don't introduce any errors of your own since you are using what they provide, or
2) They don't have a model and you need to recreate the geometry for your own use anyway.

A drawing inside a drawing may reduce the possibility of a geometric error, but as noted by this thread it introduces potential for errors in multiple other places within the value chain. Creating a Vendor Item drawing or Source Control drawing is the more recognized method of dealing with this issue.

--Scott
www.wertel.pro

 

[KENAT]

"more recognized method" - well only in so much as it's explicitly detailed in the ASME standards, while dgallup's method isn't explicitly outlawed.;-)

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[Careful]

Dgallups method is the one currently practiced at my company, and for the same reason. And I too see no benefit to remaking from scratch an already existing drawing. With lean practices and personnel reductions, we don’t have the manpower to devote to that if there’s a quicker and just as effective way. To give more background, this part is made by the vendor. We just need to assign our part number to it.

Regardless of whether this is considered an acceptable practice, I would still appreciate additional input regarding the subject of what unit and tolerance would be applied to the part in this situation. MikeHalloran above made a good point in that my original example listed “UNLESS OTHERWISE NOTED” in the tolerance block. The actual block used reads “UNLESS OTHERWISE SPECIFIED” which I believe would cover tolerance adjustment anywhere in the drawing body. I’ve attached an updated example for clarity.

It appears I need to learn more about Vendor Item, and Source Control drawings. What do you feel would be the best reference for this?

Thanks for the feedback!

 

[CheckerHater]

Try the following logic:

Statement 1 applies to everything inside of your drawing (the “red zone”) including vendor drawing.

Statement 2 applies to everything inside of vendor drawing (the “green zone”) including dimensions.

Statement 2 IS exactly what specified otherwise inside of your drawing, so statement 2 overrides statement 1 when applied to dimension.

 

[KENAT]

It appears I need to learn more about Vendor Item, and Source Control drawings. What do you feel would be the best reference for this?

I'd go to the relevant standard - ASME Y14.24.

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