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Tolerance Block "Crossout" - Per what std?

Tolerance Block "Crossout" - Per what std?

Tolerance Block "Crossout" - Per what std?

(OP)
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

RE: Tolerance Block "Crossout" - Per what std?

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." - Robert Hunter
 

RE: Tolerance Block "Crossout" - Per what std?

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

Chris Wilson
CAD Administrator
CSWP

RE: Tolerance Block "Crossout" - Per what std?

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." - Robert Hunter
 

RE: Tolerance Block "Crossout" - Per what std?

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: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

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: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Tolerance Block "Crossout" - Per what std?

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." - Robert Hunter
 

RE: Tolerance Block "Crossout" - Per what std?

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.

RE: Tolerance Block "Crossout" - Per what std?

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?

RE: Tolerance Block "Crossout" - Per what std?

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: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Tolerance Block "Crossout" - Per what std?

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." - Robert Hunter
 

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

(OP)
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

RE: Tolerance Block "Crossout" - Per what std?

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." - Robert Hunter
 

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

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

RE: Tolerance Block "Crossout" - Per what std?

(OP)
So your suggesting to put roughly +/- 1/16" tolerance on the 1/8" dimension, right?  I guess thats ok since anything out of that tolerance would make it a differant variation number.
 

Chris Wilson
CAD Administrator
CSWP

RE: Tolerance Block "Crossout" - Per what std?

drawoh, that was my point, hence option A is not to have a drawing, option B if you must have a drawing is essentially just a drawing invoking the spec and providing a reference illustration.  To me the drawing in this situation is superfluos but I'm not going to lose my job by refusing to create one, though I'd suggest we could do without.

SolidWorksGuru, your pdf example definitely needs some kind of tolerance on the 1/8" incremements.  No I don't think +-1/16" tolerance is necessarily what was being proposed, though if functionally that's what works then fine.  

You want to spec the losest tolerance that ensures function, if that's +-1/16 great, if it's +-1/8 great, if it's -0 +1/8 great.  Think about how the parts are used, the fit/function involved and tolerance accordingly.

(On another issue that came up, Just because it's a purchased part, doesn't necessarily mean no drawing is required, in fact that's specifically what some of the 'control drawings' are for.)

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Tolerance Block "Crossout" - Per what std?

If you're dealing with industry-standard purchased components, reference the standard on the drawing.  The industry standard thus overrides anything on the drawing.  For common washers, look into ASME B18.21.1 & B18.22.1 for inch-series, and ASME B18.21.2M and B18.22M for metric.  For specialized washers, look into ASME F436, F436M and IFI 534.  There other standards applicable to ISO, DIN, JIS, and many other national standards, depending on where you are sourcing and using the parts.

I don't know of any standard that says anything X'd-out is to be ignored, though it is common practice.  Of course, common practice isn't defensible in a legal context.

 

Jim Sykes, P.Eng, GDTP-S
Profile Services  www.profileservices.ca
TecEase, Inc.  www.tec-ease.com

RE: Tolerance Block "Crossout" - Per what std?

I'd disagree with fcsuper, I wouldn't edit the block.  People can get used to what the block usually says and don't always notice if you've changed it.  Having different blocks for things like cables or castings can make sense but just changing the block willy nilly can cause errors.

KENAT,

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RE: Tolerance Block "Crossout" - Per what std?

I agree with KENAT for the same reasons.  True, the fabricator should read the title block of every drawing, but in reality assumptions are often made which could result in rejected parts if the title block information has been changed.
We treat drawing format as a form and control it as such.  The title block is pretty much boiler plate, and any information that differs from that in the title block is clearly noted elsewhere on the drawing.

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

RE: Tolerance Block "Crossout" - Per what std?

KENAT,

   I will give you an example.  I specify a fan.  I provide a drawing showing the dimensions.  In notes on the drawing, I state that the fan is 12VDC, and that it delivers 60CFM at 0.1"H2O.  I try to provide more than one manufacturer and part number.

   If there are problems getting the specified fan, purchasing can find a similar fan that meets the requirement.  If necessary, they can send my specification out to a vendor to see if they have anything.

   If there are issues with the cooling, engineering can see what kind of fan I selected, and have some clue as to why I selected it.  

   Fans are standard, manufactured parts.  I cannot see why someone would do a dimension inspection on it.  My dimensions are for reference, only.  

               JHG

RE: Tolerance Block "Crossout" - Per what std?

Could it be the accent?winky smile

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

RE: Tolerance Block "Crossout" - Per what std?

KENAT,

   I was responding to your comment further up about option A.   If nothing else, I would like MRP stock codes to be based on a document somebody can locate and read.

   I set up the title blocks here.  Our title block is minimal, with boxes for the company logo, the title the drawing size, number, revision and pages, and a signature block.  We add blocks on to it, depending on what we need.  We have fabrication blocks for English and metric dimensions, we have an assembly block, and a drawing projection (third-angle) block.

   On an A-sized fabrication drawing, I do not apply the fabrication block.  I just type in a note stating that dimensions are in millimeters, and that dimensioning and tolerancing are as per ASME Y14.5M-1994.  Obviously, in the absence of standard tolerances, I have to be careful to apply complete dimensions.

   Given that ASME Y14.5M-1994 requires you to remove trailing zeros on millimeter dimensions, you have to tolerance everything manually anyway.  The standard tolerances are not much use.

               JHG

RE: Tolerance Block "Crossout" - Per what std?

For my option A, I was thinking of how standard hardware was called up, based on the washer example, not necessarily things like your fan example.  By 'to a standard' I meant something to a recognized industry or national standard such as ISO, ASME, ANSI, MIL-STD...

For your Fan example you could either go whole hog standards compliance with a control drawing or something simpler if it fits your needs.  I agree that just having a vendor part number isn't always adequate.

KENAT,

Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?

RE: Tolerance Block "Crossout" - Per what std?

KENAT,

   On second thought, it was the accent.  Yeah, it was the accent.  smile

               JHG

RE: Tolerance Block "Crossout" - Per what std?

KENAT,

I know where you are coming from regarding editing title blocks.  I instinctly had the same impression.  However, after implementing the modifiable title block at my company, no issues have arise, and there's even been some grateful comments from various parties.

Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group

RE: Tolerance Block "Crossout" - Per what std?

I've actually encountered the issue of errors being caused by the changed title block tolerance, so hence I'm generally a'gin it.winky smile

Back in the UK though where, being mostly metric we only had a single value block tolerance, not varying by decimal places, we just put whatever value was most appropriate for the drawing.

KENAT,

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