Tolerance block: to use or not to use? 1

[ronw06770]

Gentlemen,
I have been in design/drafting and engineering for 35 years and using GD&T ASME Y14.5 for just as long. Now, at my current employment, they are not putting a tolerance block, or material block or a 3rd angle block. They put the tolerance block on a drawing if there is a dimension that needs a tolerance. Same for material and 3rd angle projection. My contention has always been, and I have taught that: "if you go way back to pre-printed format you wopuld have all block already there". If they apply, then the person using the drawing has the information they need. If the drawing doesn't have dimensions (like a assembly dwg) then the tolerance doesn't apply. Having rambled and going in a BIG circle, Does ASME Y14.5 determine or specify that all information blocks within the format have to be there? Or do you only add them when needed?

 

[dgallup]

Can't tell you what ASME requires but ISO 7200 says only 3 things are absolutely necessary:

A) Registration or identification number
B) Drawing title
C) Legal owner

Then indicative items that are only mandatory if the drawing can not be understood without them:

D) Projection
E) Scale
F) Linear units

Then technical items dealing with methods and conventions MAY be added:

G) Method of indicating surface texture
H) Method of indicating geometrical tolerances
J) Values of general tolerance
K) Other standards in this field

Then administrative items MAY be included:

M) Size of the drawing sheet
N) Date of the first issue
P) Revision symbol
Q) Date & description of revisions
R) Other administrative info (signatures, etc.)

Multiple sheet drawings SHOULD show the sheet number and total number of sheets.

Personally, I can't imagine making a drawing without ALL of those items but maybe I lack imagination.

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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.

 

[mdambros]

According to ASME Y14.1-2012 section 6.2 Contents it addresses what items are required to be on the title block.

Block A) The name or name and address of the company or original design activity whose drawing number appears in the drawing number block. On continuation sheets, this block is required in the absence of a design activity identification (DAI)

Block B) Drawing Title

Block C) Drawing Number

Block D) Sheet revision block. This block may be omitted when a revision history block is included on the sheet.

Block E) Block for names and dates relative to the preparation and approval of the drawing. When applicable the contract number shall be included within this block.

Block F) Approval by the design activity when different from the source preparing the drawing. This may be necessary when a contractor-subcontractor condition exists; otherwise this block may be absorbed into block E, or it may be used for other purposes.

Block G) Approval by an activity other than those described in blocks E and F. Where not required, this block may be absorbed into block E, or it may be used for some other purposes.

Block H) Predominant scale of the drawing sheet. Enter "NONE" when no scale is used. Each sheet may have a different predominant scale.

Block I) Design activity identification (DAI). When required for identification of the original design activity whose drawing number is used. For the commercial sector where there is no requirement for the DAI, the DAI block may be left blank or eliminated.

Block J) Drawing size designation.

Block K) Actual or estimated weight of the item when required. This block is shown on sheet one only.

Block L) Sheet Number. Enter the appropriate sheet number beginning with the numeral 1. The drawing shall be prepared initially using consecutive whole numbers. When all sheets are maintained at the same revision level sheet one shall indicate the total number of sheets. When all sheets are not maintained at the same revision level, the revision status of sheets block lists the total number of sheets and the total number of sheets is not required in this block.
Section 7 addresses the revision history block. It is to be located in the upper right hand corner and space shall be reserved to extend the history downward. I don't see where a revision history block is required though.
Under section 10 additional data blocks are addressed. It states blocks containing various types of additional data when required, shall be added adjacent to the title block and in the same respective location on the drawing sheets.

The spec details three commonly used blocks.

10.1 Angle of Projection Block

10.2 Dimensioning and Tolerancing Block

10.3 Application Block - Optional

Perhaps the materials block would fall in this category as well. I don't see it mentioned in the spec.

Hope this helps.

 

[drawoh]

ronw06770,

There is nothing in ASME Y14.5 that specifies that you must have a title block.

I have created a drawing title block that is absolutely basic. It identifies the company, the drawing title, number, revision, sheet, a signature block, and a note stating that we own the drawing and that you cannot use it without our permission. We have separate blocks we stick on to provide additional information, like drafting standard and tolerances.

On some A-size forms, I have saved space by leaving off the fabrication block. I have a note on the drawing specifying the drafting standard. Obviously, I need to completely dimension the part. Typically, the part is extremely simple, otherwise, I would have used a larger sheet, and the fabrication block.

--
JHG

 

[ewh]

Y14.5 is intended to address geometric dimensioning and tolerancing, so it's not surprising that subjects related to drawing format are not found there. As pointed out by mdambros, refer to ASME Y14.1-2012 for such issues.

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

 

[Belanger]

However, Y14.5 does say in paragraph 1.4(b) that "dimensioning and tolerancing shall be complete so there is full understanding of the characteristics of each feature." This may be expressed on the "drawing or in a CAD product definition data set."

Whether you use a title block tolerance or not isn't prescribed; but whatever it takes to make the requirements clear.

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

 

[ewh]

ASME Y14.1 is a cited standard in ASME Y14.5, for what it's worth.

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

 

[ewh]

(Gee, I wish I could edit, or at least reflect longer before posting ;-))

You don't need any format if only following Y14.5. Drawing numbers, signatures, standard format sizes, etc are not in the scope of that standard.

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

 

[KENAT]

What's worse, having no tolerance stated or potentially the wrong tolerance invoked because it defaults to the block tolerance?

At a previous employer there was a toleranc 'block' in the format but it didn't have any numbers in it by default - you had to put in numbers that made sense. It was in the UK and we didn't use the tolerance varying with decimals (plus half the drawings were metric so that approach wouldn't have worked for them anyway).

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