Is there anyone who does not use titleblock tolerances?

[fsincox]

I am trying not to overload other threads so I started this one for this, Do any of you really not use title block tolerances on your drawings? What type of industries/parts/assemblies are they?
I myself am in aerospace now: many sizes of fans, small air valves and actuators. Very small quantities that the big guys leave behind, not large quantities. Previously, I was in large specialty machines and transfer line machine tools mostly for the auto industry. Huge castings and weldments, all kinds of machined parts, and high precision machining parts, again small runs not likely to throw away after making a large investment. I believe this is one reason I have seen such bad fabrication tolerance practices, always has to be 2 place dimensions. What does it mean? ABSOLUTELY NOTHING!! Just a picture of what you want and you take what you get.
Frank

 

[Belanger]

Several companies that I work with have done away with traditional title block tolerances. They have a general note that says "all undimensioned features are given in CAD model and are basic." Then they have a general profile of a surface tolerance of something like 2 mm that covers all items not directly toleranced.

I guess that's still a title block tolerance, but not the plus/minus variety.

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

 

[ctopher]

We use them. All companies I have worked at use them.
All dwgs need tolerances on the face somewhere, in the block or with the dim.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[drawoh]

fsincox,

The titleblock tolerances require you to show the trailing zeros of your dimensions. In ASME Y14.5, you are not to show trailing zeros on your metric drawings. I don't.

If it takes me more than two minutes to apply tolerances to each and every dimension on my drawings, it is because I discovered that my intended tolerance did not work, and I had to go back and modify the design. Tolerance stacks are a pain in the butt sometimes.

There is a lesson in there somewhere.

JHG

 

[KENAT]

drawoh, you can still have a block tol with metric drawings, we did in the UK, we just had a single value not the typical varying with DP you see in the US.

Heck, if you're willing to right your own little disclaimer you could do trailing decimals on metric, it would be your variation from 14.5 which comes at the risk of causing confusion.

You could be really european and invoke iso2768 but I'd rather not thank you.

fsincox, I thought similar, or at least complaints about over reliance on block tols rather than calculating functional tols had been discussed before in detail.

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[fsincox]

ctopher,
My point will be erroneous tolerances are no better than none if you think about it, people become numbed by it.

j-p
I have been advocating that for about 15 years now. I want to combine the general profile to a master framework with an ISO tolerancing structure; unfortunately I need to work for ISO people first.
Frank

 

[fsincox]

JHG,
"fsincox, The title block tolerances require you to show the trailing zeros of your dimensions. In ASME Y14.5, you are not to show trailing zeros on your metric drawings. I don't."
Sorry I don't get your point here. I detest the practice of tying tolerance expression to the number of decimal places I feel it is too easily abused.

Frank

 

[ctopher]

However many decimal places you use, use same decimal place tolerances per the dims.
If no tolerance shown with the dim, use a tol block.
Show no tol or tol block, do not expect good results from finished parts.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[PeterStock]

Our major client does not use title block tolerances, all dimenensions have a tolerance or are basic with tolerance in a GD&T. In fact historicaly if the dimension did not have a tolerance it was basic.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[fsincox]

PeterStock,
What you stated is what I realised when I was first trying to get my mind around the ISO system, years ago. I suddenly realised that in the end it is only because of our "inbreeding" that we think of decimal places as implying tolerance ai all. What exactly do you mean or can you expand on "historically"? Do you know thw history of how this came about?
People claim they care about these issues. I have seen all my life companies take jobs from ISO companhies and not even bother have a copy of them or to understand their standards.
Frank

 

[KENAT]

thread1103-199111 is I think the one I was recalling though thread1103-206463 has some stuff.

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[PeterStock]

By historicaly, I am refering to our major clients previous drafting standards. They now use ASME Y14.5-1994 plus a company spec for company practices. In the past they had there on version of Y14.5. This was almost identical to Y14.5, but there were diferences including non-toleranced dimensions being basic. We do use the old spec when revising existing drawings.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

http://www.infotechpr.net

 

[fsincox]

Thanks guys
I had not got to those threads yet I am starting from the back (pg 54)and only about to pg 50. Those are good ones. That is why I decided to read through the posts here, I finally learned how to use archive too, Is there a limit to the archive?
Frank

 

[KENAT]

fsincox, play around with the different search tools at the top of the screen. None of them are perfect, but with practice they have some ability.

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[drawoh]

(Aerospace) 23 Feb 10 20:52
JHG,
"fsincox, The title block tolerances require you to show the trailing zeros of your dimensions. In ASME Y14.5, you are not to show trailing zeros on your metric drawings. I don't."
Sorry I don't get your point here. I detest the practice of tying tolerance expression to the number of decimal places I feel it is too easily abused.

That is sort of what I was saying. Setting the decimal places of your dimensions is really not much more convenient than thinking about and setting the tolerances individually. The tolerance block ought to have and usually has a statement like "UNLESS OTHERSISE SPECIFIED", so you can do anything you want.

I am annoyed and frustrated at people who, obviously, have populated the drawing with three decimal English, or two decimal metric dimensions, and are satisifed that they have toleranced everything. This sort of works in a machine shop, but is completely disfunctional for welders.

JHG

 

[TheTick]

I worked at one place where ALL dimesnions had explicit tolerances, usually in the form of limit dimensions. No title block tolerances.

 

[dgallup]

We also use one default tolerance for linear dimensions and one for angular dimensions. I set it fairly generously for the type of parts we make. It is just as bad to have one really small default tolerance as to put 3 decimal dimensions all over the place.

Anything that has to be closely controlled get an explicit tolerance and probably a critical characteristic symbol too.

 

[jerry1423]

I get the impression that ISO standards moved away from title block tolerances. I can understand why that would do that ... I have seen some very careless tolerancing practices with the title block tolerances.
But with that said the vast majority of companies still have them and I don't see them going away.
With CAD it is very easy to add a tolerances to individual dimensions, and I prefer that - with some exception.

 

[fsincox]

jerry1423,
I would be VERY interested to know how you have come to that conclusion. If the drawings reference something like: ISO 2768-mH (or similar) it is all in there. They just don’t do it like we do.
Frank

 

[dgallup]

The ISO standard is really weird (IMHO) in that the default tolerance is a function of the nominal value. So if you make your dimension a little bigger or smaller and cross the threshold to the next size range the tolerance changes. I supposed if you used it all the time it would become second nature but I don't like my tolerance changing just because the nominal changed from 29.9 to 30.1 mm.