Dimensions and Detail views 2

[SBaugh]

Good Afternoon everyone! - I hope someone here can give me some insight on these questions.

1) Does ANSI allow for Detail views to have a Broken out section view within it? I don't mean add the Broken out section in a Front view and then detail the area, simply Detail the area, then add the Broken out section?

2) If there is a Dimension on a drawing without a Tolerance and there is not a Tolerance block on the drawing, would that Dimension be considered as a theoretical perfect location, similar to a Basic dimension in GD&T? (Note: we are not using GD&T on our part models)

Thanks,

Scott Baugh, CSWP
Berry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader

http://www.scottjbaugh.com

"If it's not broke, Don't fix it!"

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[CheckerHater]

1) I’ve never heard of it being explicitly forbidden. This topic is covered in ASME Y14.3. I don’t have a copy of the standard and cannot guarantee there isn’t “small print” somewhere. Your CAD system, on the other hand, may not allow you to create view like this.
2) No, this will be considered sloppy design work. Think of specifying some tolerances somehow somewhere.

 

[SBaugh]

1) What I would like to do is get a copy of that, because that would allow me to complain to our CAD company is not following ANSI Standard and force this into a fix.

2) I am not saying that what we are doing isn't sloppy, but the way its done currently is not IMO being done properly.

We tolerance our parts as needed, we do not use GD within our parts (plastic parts). But there are areas where people have pulled information from GDT standards and have been using them incorrectly. I am writing a Standard Operating Procedure (SOP) to fix stuff like this from occurring in our future drawings.

The problem really comes down to the fact we might be one company, but we have different divisions that don't agree on anything. For example one wants to have a Tolerance block on the drawing, where the other does not. There are reason for both which make for a much longer story, but I have to make a single drawing template that works for both divisions.

Here is part of the Title block

You can see on drawing it lists a "Basic Dimension" that reflects a Dimension on our drawings that has no tolerance for one division (without the tolerance block). The other division allows the "Basic Dimension" to follow the Tolerance block.... which makes no sense to me. It should either be renamed to something other than Basic or needs to be removed from the Drawing entirely. Which is why I asked my question about Dimensions without a Tolerance, would it be understood its similar to a Basic Dimension, but without the note, or the Box surrounding it?

Those that are not using a Tolerance block will never setup a tolerance like you suggested, nor will they use a Tolerance block. They will only setup Tolerances on areas that need it. Our Plastic parts are unique and are not held to a tolerance like some are. We are talking about customer packaging.


Scott Baugh, CSWP
Berry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader

http://www.scottjbaugh.com

"If it's not broke, Don't fix it!"

faq731-376

 

[KENAT]

originally in thread174-353979 and this was my post there

1. ASME Y14.3-2003 doesn't appear to explicitly say whether you can put a Broken out section view within a detail view. Sections 2.9 'Details' & 3.10 'Broken-Out Sections' seem to be the relevant text, I didn't look too closely at the rest to see if there was a general note about combining types of view. While I'm not sure my current version of my CAD system allows me to do it I don't think I can say it's wrong - so long as it's clear what's going on.

2. Only if you have a general note saying something like "UNTOLERANCED DIMENSIONS LOCATING TRUE POSITION ARE BASIC" (ASME Y14.5M-1994 5.2.1.1(b). However trying to go too far cherry picking what part of a standard you invoke can get complicated.

https://www.asme.org/products/codes-standards/y14-3---1994-multi-and-sectional-view-drawings

It would be a real stretch to say your CAD vendor isn't complying, given that ASME don't explicitly say it's good or not and don't give any examples or info on application etc.

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[ewh]

Apparently your company isn't following ASME Y14.5 (which covers dimensioning as well as tolerancing). Too bad. The first fundamental rule of dimensioning states "Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum, or stock (commercial stock size). The tolerance may be applied directly to the dimension (or indirectly in the case of basic dimensions), indicated by a general note, or located in a supplementary block of the drawing format. See ASME Y14.1 and ASME Y14.1M."
Note that "indirectly in the case of basic dimensions" means to use the tolerance in the supplied related feature control frame (or default to shop tooling tolerances).
Of course if you aren't following that standard the above means nothing.
How can the parts be inspected without tolerances to establish what is acceptable?

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[CheckerHater]

How can the parts be inspected without tolerances to establish what is acceptable?

Well, it's plastic. After you invest several tens of thousands of dollars into the mold, you measure the part and change the drawing to match.

 

[ewh]

Ahh...

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[KENAT]

Not necessarily CH.

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[ewh]

I understand the logic, but there should still be a tolerance included even if the dimension changes with tool wear. Nothing is "perfect".

As to Scotts first question, I don't believe there is anything in the standards preventing a broken out section within a detail view, as long as intent is clear. I have done this in the past. Seems like a software limitation to me.

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[ctopher]

I agree with ewh.

The plastic part, and its mold, need tolerances. The mold is tolerance based on the part shrinkage.
If a dimension has no tolerance, and there is no tolerance block, the machinist can only do his/her best to meet that dimension. If it's off by some amount, it can not be rejected.

Chris
SolidWorks 13
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[CheckerHater]

It was a joke.

It could be funny, if it wasn’t so bitter.

I’ve actually seen it done as “best practice” of a sort.

You can actually control the dimensions of your molded parts, especially ones made from thermosetting plastics. Different cooling time can do miracles. If you run the mold yourself. If it’s the guy on the other side of the globe and he is in a hurry – good luck.

Now, I have a question for OP titleblock:
Critical dimensions are the ones you check all the time.
Reference dimensions you never check.
What are your “basic” dimensions, what is it you do to them?

 

[SBaugh]

Another reason why some dimensions do not have a tolerance, nor a tolerance block, is because those dimensions are used for our Tooling Engineers to create the Shrinkage drawing. We are not making the Shrinkage drawing, we are making the product to what we want the final product to be. So in our eyes these dimensions are perfect theoretically so is the part. After its molded, we might go back and update the Manufacturing drawing (not the same as shrinkage) with a tolerance. The Customer drawings always stays reference, we might have to update it if the dimension changed with approvals, but rarely does that happen.

So the answer I figure for Item 2 is technically, it needs a tolerance, but if doesn't its not considered perfect. Even though it does not have tolerance or a tolerance block on the drawing. - I think removing or renaming the BASIC callout is the best solution and adding a note explaining what the dimension is.

As for Item 1 - Does anyone have any documentation that says that ANSI allows for a broken out section view to be in a detail view? I understand it might be a limitation to the software, but that's not what I was asking... I was told that this ANSI standards does not allow this to happen. Which is why I ask is there any documentation that supports this sort of behavior in ANSI standards. If so, and I can get that information sent to me, then I can take that information to the Software vendor and show them they are wrong and that they need to add this functionality to the software.

Thanks for all your replies!

Scott Baugh, CSWP
Berry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader

http://www.scottjbaugh.com

"If it's not broke, Don't fix it!"

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[KENAT]

Sbaugh, if there was a definitive statement it should be in ASME Y14.3 per my initial response to your original thread.

There is apparently a newer version than the one I have so perhaps that says something different.

https://www.asme.org/products/codes-standards/y143-2012-orthographic-pictorial-views

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[ewh]

Nothing that I can find in ASME Y14.3-2003 precludes a broken section in a detail view...

Detail Views - ¶2.9 "In areas where clarification is necessary or to better illustrate a complex configuration, a detail is shown elsewhere on the drawing to show small features at an increased scale and provide additional information. See Fig. 23. Figure 23 shows a detail. It also shows additional information since the fastening device is included. View and zone referencing as described in paras. 1.7.2 and 1.7.7 may be used. The scale of the detail shall be noted."
(note that additional information could also arguably include a broken-out section)

Broken-Out Sections - ¶3.10 "Where it is necessary to show only a portion of the object in section, the sectional area is limited by a break line, and the section is called a broken-out section. No cutting plane is indicated."

“Know the rules well, so you can break them effectively.”
-Dalai Lama XIV

 

[SBaugh]

Thanks for all your replies! It has been very helpful!

Scott Baugh, CSWP
Berry Plastics
Cad Admin\Design Engineer
GEASWUG Greater Evansville Area SWUG Leader

http://www.scottjbaugh.com

"If it's not broke, Don't fix it!"

faq731-376