General Tolerances
General Tolerances
(OP)
I have been trying to find general angle tolerances to put into drawing title blocks but cant find any. What are general tolerances for angular tolerances of machined and bent angles? Can anyone help with what a standardized value for these would be?





RE: General Tolerances
TOLERANCES SHOULD BE DECIDED BASED ON FUNCTION FIRST.
Sorry for shouting but questions like this will bring up that old debate. Most posters here subscribe to that philosophy and many feel that 'block tolerances' or 'standard tolerances' or the like are over relied upon by many designers/engineers to the detriment of performance etc. There are plenty of threads bemoaning that if you want to look.
So, please explain what you mean by General tolerances.
Are you more interested in typical process capabilities? Again quite a few threads on this and no simple answer as it varies so mucy by vendor/machine capability, part size, part material etc.
If you just want examples of what peoples block tolerances are my place says +-0.5° which I think is fairly typical.
KENAT,
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RE: General Tolerances
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?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: General Tolerances
For what it's worth my current company's default angle tolerance is +/- 1 degree, and I've seen as tight as 0.5 and as loose as +/-5 (both in degrees), although I had a very hard time believing the +/-5 would ever produce consistently acceptable parts for any application.
RE: General Tolerances
What do you mean by "General Tolerances"? I have title blocks set up to say ±1° as the default. I could have just as easily set it to ±0.5°.
The ANSI/ASME Y14.5 standard, at least since 1982, has not allowed trailing decimals on millimeter dimensions. This means that you must set tolerances or geometric controls on each and every metric dimension. This is not particularly difficult, and as noted above, it leads to better quality drawings.
RE: General Tolerances
RE: General Tolerances
thread1103-222161: General Drawing Tolerances
thread1103-199111: Fractional dimensions
RE: General Tolerances
Be very cautious with ISO 2768. There as several threads, for example thread182-247563: A different perspective on ISO 2768, discussing/questioning this thread for several reasons that can perhaps be summarized as:
1. The information used to create the tolerance classes etc. is probably out of date.
2. Conceptually it's basically saying that manufacturability is more important that function.
3. There is confusion on how aspects of it are applied/interpreted.
4. There is a get out clause at the end of the standard that says just 'cause a part doesn't meet the tolerance stated doesn't mean it should be rejected but you should look at function. Some believe this is just to allow for production permits/deviations whatever you call them. However it kind of conflicts with the idea of the drawing being driven by function. If the drawing doesn't record functional requirements what does?
KENAT,
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RE: General Tolerances
As mentioned, general tols should be used with caution, and there is no one size fits all.
For example, with sheet metal, you cannot really use a general tol unless you have flat parts or long flat areas. The reason is that very bend, cut or other feature is affected by the feature it is being dimensioned from. One bend may put your tolerance at +/-.016, but dimensioning across two bends immediately doubles that.
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: General Tolerances
RE: General Tolerances
drawoh (Mechanical)
11 Sep 09 15:35
vctinc,
What do you mean by "General Tolerances"? I have title blocks set up to say ±1° as the default. I could have just as easily set it to ±0.5°.
The ANSI/ASME Y14.5 standard, at least since 1982, has not allowed trailing decimals on millimeter dimensions. This means that you must set tolerances or geometric controls on each and every metric dimension. This is not particularly difficult, and as noted above, it leads to better quality drawings.
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My company designs everything in metric & we have default tolerance blocks on every drawing. We just use a single value for linear dimensions & one for angular dimensions. Problem solved. I hate the ISO default tolerance blocks where if your part changes from one size group to the next the tolerances jump up or down.
And I frequently use +/-5 degrees for angles, got tired of the QC inspectors rejecting good parts because the 45 degree x .5 max chamfer was 48 degrees.
I like relatively loose default tolerances, if a dimension needs to be tight then call out what you need. And if it's really important use a special characteristic symbol to call attention to it. Way to many lazy drafters making impossible drawings with tight default tolerances and every dimension nominal with no other tolerance.
RE: General Tolerances
If you are manufacturing to ISO spec's and sell to the rest of the world or for many international US companies -big problem.
You would not want to use the same tolerance field for a 60mm dia that you are using for a 12mm dia , would you?
If that is what you are doing - good luck to you.
RE: General Tolerances
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: General Tolerances
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: General Tolerances
http://ww
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: General Tolerances
RE: General Tolerances
It is just that I would rather work to a worldwide standard than work with something used by a select number of manufacturers.
RE: General Tolerances
ISO2768 is based on a DIN standard, and while I haven't seen a massive sampling, I've only seen it used on German drawings that I can recall.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: General Tolerances
I work for a major UK Defence company, and by referring to BS8888 on the drawing, I must work to the relevant Tolerance Standard.
RE: General Tolerances
Interesting, I worked UK defence too and the tolerance concepts of iso2768 or the BS EN equivalent never came up, either in our drawings or any of our customers/suppliers. This was 99-04, I looked through BS8888 on numerous occasions and don't recall seeing it.
I still don't like 2768 though
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?