Tolerance Block "Crossout" - Per what std?

[SolidWorksGuru]

Our company has always crossed out (big "x" from corner to corner) the Tolerance Block on our std sheet formats whenever it didn't apply to the drawing. For example, if it's a control drawing of a WASHER, we will specify a size of 0.094"ID x 0.250"OD x 0.032"THK. Those are parameters that purchasing uses to order the right size, but I don't want inspection to be checking the washer dimensions within .005. So, we cross out the Tol Block to indicate that it does not apply.

This practice is now being chalanged by our new director of QA!!!

Does anyone know what standard this comes from?

Chris Wilson
CAD Administrator
CSWP

 

[ewh]

I have only ever crossed out the tolerance block when other tolerances were included in the notes or body of the drawing, or where all dimensions were reference.

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

 

[SolidWorksGuru]

But do you know if there is an ANSI/ASME/ISO standard that governs this practice?

Chris Wilson
CAD Administrator
CSWP

 

[ewh]

No, I don't know of any standard which governs the use of untoleranced, non-reference dimensions, and doubt that one exists. Perhaps someone else here can point us to the applicable standard.

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

 

[KENAT]

If you don't put a tolerance, then you don't set a pass fail criteria. As ewh says it's one thing to cross out the block and replace it, but what you are doing is virtually making the dimensions reference only.

Similar came up a few weeks ago, regarding control drawings, where I believe it was determined they should have tolerances.

ASME Y14.24-1999 defines the requirements for control drawings so I'd look there, however, it doesn't go into much detail on the tolerancing issues. Your example sounds like maybe a Procurement Control Drawing, section 8.1 for which the example given doesn't explicitly indicate whether or not the dimensions are toleranced.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[drawoh]

SolidWorksGuru,

Why is your director of QA objecting to the crossed out block, and what does he want to do instead?

You can apply dimensions to your washers as reference dimensions and leave the tolerance block intact, but I an not sure what this accomplishes.

JHG

 

[TheTick]

No need to cross out anything. Notes supersede the title block. Explicit tolerances supersede notes.

 

[KENAT]

Good point drawoh. Is the QA guy objecting specifically to crossing out the tol block, or is he objecting to the lack of pass/fail criteria?

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[ewh]

Good point, Tick. The easiest solution would probably be to make all dimensions reference, or a note to that effect, and leave the tolerance block alone.

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

 

[vigildesign]

The only place I can recall seeing the tolerance block alteration is in the Global Drawing Requirements Manual, 10th ed., section 5-23. It allows a user to line through tolerances shown on the block and a flag is located within the box which refers back to the note section with different tolerances.

 

[SDETERS]

Usually with a washer the Dimensions go back to a certain standard. This standard needs to be meet. What do you put on the drawing to make sure the dimension meet the standard? Do you put reference dimensions or do you replicate the dimensions that are on the standard with the appopriate tolerances?

 

[KENAT]

If you are actually buying them to a standard then:

A: do you really need a drawing?

B: if you want a drawing, then probably best to make true reference dimensions and somewhere state that the washer is to standard xxx # yyy.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[ewh]

I too wonder why a drawing is necessary. If you require a drawing, all you really need is a note stating that the washer is to be per specification #XXXXX, (same dash numbers apply, if applicable). Make the dimensions reference. Otherwise, QA will be responsible for checking every dimension.

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

 

[drawoh]

KENAT,

If the item conforms to a standard, why can't the specification control state that the part must conform to the standard? Now, the standard becomes the inspection document.

JHG

 

[ctopher]

If it's a purchased part, no need for a drawing.
Otherwise, everything on the drawing is used to control the part. If it's crossed out, nothing to inspect or control.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[SolidWorksGuru]

The washer was just one example. Please see the uploaded file and advise.

I'm just trying to decide wether this is a good practice or not.

Chris Wilson
CAD Administrator
CSWP

 

[SolidWorksGuru]

Sorry, forgot to add the link.
(first time user)

Chris Wilson
CAD Administrator
CSWP

 

[ewh]

In your example, you need some kind of tolerance on the 1/8 inch increments; perfection is not an option.

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

 

[ctopher]

I agree. Anything dimension on any document needs a tolerance.

Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08; CATIA V5
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion

 

[MechEng2005]

I think any standard will require some sort of tolerance or spec.

However, I do understand why this would be a hassle, and typically not necessary. I can also see why, in an ideal case, it should be there.

The way I see it, you have 3 options:

1) Conform to the QA director and put a tolerance or spec.

2) Cross out the title block and add ridiculous tolerances. For example, a 2" washer could have and ID of
2 1/16" +1" -1/32"

3) Create a new title block to paste on to appropriate drawings with ridiculous tolerances that are ridiculous for any application. For example, "Fractional, less than 36" = +/- 120".

If you go with options 2 or 3, I don't want to hear about it. If I were the vendor, I would probably send you ridiculous things for the fun! For option 2, a standard 2 1/2" washer. For option 3, assuming a piece of bar or similar, I would send only a bill and say it was 36" below nominal, which is within stated tolerance.

No offense intended. Just having a little fun and amusing myself today...

-- MechEng2005