42 Replies Latest reply on Oct 8, 2009 4:35 PM by Matthew Lorono

    ASME Y14.5 Gurus

    Barna Madau
      I've posted a couple of threads now on the improper way SW displays basic dual dimensions. I can't find a place in the std. the shows the proper way it should be displayed. Could someone help out? Also, I might toss in the problem w/ centermarks scaling w/ the drawing scale.

      I'll keep looking- but I'd appreciate some help.

      thanks,
      BM
        • ASME Y14.5 Gurus
          Steve Calvert
          Barna, this might start off a topic that won't end.

          I'm no ASME guru but I think because you don't see Basic Dual Dimensioning in the Y14.5M 1994 standard is because most people frown on dual dimensioning and when you start making both dimensions basic you sort of contradict yourself or at least with conversions of dimensions it may not be clear as to what you want.

          Steve
          • ASME Y14.5 Gurus
            Matthew Lorono
            Dual dimensions are not supported by the ASME standards. From a certain point of view, they technically violate ASME Y14.5M-1994. I wrote about this a while back: http://www.fcsuper.com/swblog/?p=72
              • ASME Y14.5 Gurus
                Eddie Cyganik

                Matt,

                Great write-up.

                Interestingly, the final statement in ASME Y14.5 1982M is:
                "Dual dimensioning is no longer featured in this Standard."

                To me, this implies that Dual Dimensioning will be featured somewhere else. However, I agree with you, as it is not.

                Also, in the 1982 version they describe two methods that were used for dual dimensions, including figures or examples.
                Position Method & Bracket Method. In both methods, the information could be displayed two ways:
                Primary on Left & Secondary on Right
                or
                Primary on Top & Secondary on Bottom

                Position Method 1:
                Ø1.000/25.4 (single line, forward slash used as a seperator)

                Position Method 2:
                Ø1.000
                --------
                25.4 (stacked, horizontal line used as a seperator)

                Bracket Method 1:
                Ø1.000[25.4] (single line, no seperator)

                Bracket Method 2:
                Ø1.000
                [25.4] (stacked, no seperator)

                In the examples for basic dimensions, regardless of method used, the "stacked" display is shown. All data is encompassed by a single basic box.

                In the examples for all other GD&T, regardless of method used, the "single line" display is shown. Again, all data is encompassed by a single box or control frame.

                The last known version where dual dimensioning is used is ASME Y14.5 1973M.
                  • ASME Y14.5 Gurus
                    Barna Madau
                    Geez, I guess I'm stuck between a rock and a hard place. My customer is insisting that my drawings confrom to their company standard, and that is dual dimension. I was hoping I had a leg to stand on by citing some paragraph in the standard for my VAR to send to the folks at SW... It seems that would give a greater chance for a fix than "this just looks better"... oh well.

                    I'll send it off anyway, maybe w/ some screenshots showing the "right" way and the way SW currently does it.

                    Thanks for the help.

                    BM
                      • ASME Y14.5 Gurus
                        Steve Calvert
                        I don't like dual dimensioning but that doesn't mean it can't be done properly. The one thing that needs to be stated is what units the file is in. Some of our castings are in imperial units but the drawings are dual dimensioned. I would rather NOT have this but the files are several years (decades) old, so we haven't changed them. If your customer wants dual dimensions, give them dual dimensions.

                        Steve
                          • ASME Y14.5 Gurus
                            Eddie Cyganik

                            Steve,

                            In the titleblock, every drawing should state something to the effect:
                            DO NOT SCALE PRINT
                            UNLESS OTHERWISE SPECIFIED
                            ALL DIMENSIONS ARE IN INCHES [mm]

                            If dual dimensions are not specified in the titleblock, then a general note should be added as follows:
                            X. DIMENSIONS AND/OR QUANTITIES SHOWN IN BRACKETS ARE MEASURED IN METRIC UNITS.

                              • ASME Y14.5 Gurus
                                Robert Berry
                                Interesting discussion.

                                My opinion of dual dimensioning, bad, bad, bad, bad.........BAD!

                                Here's my experience and resons why.

                                I work for a Japanese company who want us to manufacture thier product in the U. S..

                                Our shop puffs out it's chest and says we are an English shop we will not work in Metric.

                                The Japanese say we want to inspect your parts and we will be inspecting in metric to your prints.

                                Brilliant solution, convert all of the metric prints to English with dual dimensions, (English and Metric with tolerances).

                                Problem one: is there a standard?

                                Yes, Din 370 states very clearly how to convert English to metric and Vice versa.

                                Problem two: there is no standard for dual dimensioning, so we wing it.

                                Problem three: The Din standard has diffrent levels of accuracey for the conversion and requires truncation in the direction of the tolerance reguired at our level of precision.

                                This simply means you always round down for shafts and up for holes, as we are already tolerancing to tenths we are consitently decreasing our tolerance zone. Not good.

                                Problem four: Now the shop is pissed because we are taking away tolerance from parts that are already tough to manufacture.

                                Solution: Tough, you wanted it you got it.

                                Conclusion: by dual dimensioning we have added, cost of manufature, dissention among the ranks, and confusion with our parent company over inspection and tolerance control.

                                If we had just stuck with metric all of the angst and confusion dissapears.

                                Regards,
                                B. B.


                                  • ASME Y14.5 Gurus
                                    Barna Madau
                                    Well, thanks for all the input. Several years ago I was working for a company that dealt in inches, but after a while decided they wanted to swtich to mm. We were using a lot of overseas vendors, and the products we were manufacturing were all intended to fit on other products that were primarily desinged using metric units, so it made sense. We all fought against it anyway, but after that fact, looking back, I'm glad we did. It made life a lot easier, and we were able to produce cleaner drawings in the end. Now I'm frightened of having to go back to inches again...

                                    What are your thoughts on tolerance blocks in the title block? I personally don't like them.. I prefer to individually tolerance every dimension on the drawing. They don't even work w/ metric units since you are supposed to surpress trailing zeros anyway.

                                    BM

                                      • ASME Y14.5 Gurus
                                        Steve Calvert
                                        Barna, we use a sheet tolerance block here in the states but when I do ISO documents for our friends across the pond I use the ISO 2768-1 General Tolerance Satndard.

                                        Steve
                                        • ASME Y14.5 Gurus
                                          Eddie Cyganik
                                          Barna,

                                          In our title blocks, we have the following.

                                          Drawing with Metric Units: (ISO Drawing Standards)
                                          DIMENSIONS WITHOUT TOLERANCES PER ISO 2768-m K
                                          Side Note: For Holes & Shafts we follow DIN ISO 286

                                          Drawing with Imperial Units: (ASME/ANSI Drawing Standards)
                                          TOL ON ANGLE ±2° 2PL. ±.015 3PL. ±.010

                                          Please not, there is an Order of Precedence for tolerances as follows:
                                          #1 Tolerance shown directly on a dimension on the field of a drawing.
                                          #2 Tolerance identified in a flag note shown in the general notes and referenced/attached to dimension on the field of a drawing.
                                          #3 Tolerances shown in title block.
                                          • ASME Y14.5 Gurus
                                            Dwight Livingston
                                            Eddie

                                            This is Barna's post that I was referring to . . .

                                             

                                            Originally posted by: Barna MadauWhat are your thoughts on tolerance blocks in the title block? I personally don't like them. I prefer to individually tolerance every dimension on the drawing. They don't even work w/ metric units since you are supposed to surpress trailing zeros anyway.

                                            What I thought he meant, and at least what I meant, was that for metric dimensions you cannot use one number of places to the right of the decimal point to indicate one general tolerance and another number of places to indicate another general tolerance. For example, a title block stating .X = +/-.2 and .XX = +/-.05.

                                            You are right, that doesn't mean you can't have one general tolerance.

                                            It does mean, though, I have to go change some details of our division's standards. Fortunately so far we have been using very little metric.

                                            This forum is great for picking up stuff.

                                            Dwight
                                              • ASME Y14.5 Gurus
                                                Robert Berry
                                                Gentleman,

                                                Again, it has been my experience working with companys from Germany, who use DIN, and companys from Japan, who use JIS, the general tolerancing on drawings is handled in the tolerance block on the format.

                                                They adjust tolerance both axially and radially according to the size of the part.

                                                The larger the feature the greater the tolerance range.

                                                There is no such animal in Metric that uses trailing zeros for accuracy that I have seen, as we have on English drawings.

                                                A millimeter is a millimeter, I don't know chapter and verse how the machinist would view that, .039, .0394, or .03937 if it were in inches.

                                                It's simply a millimeter of tolerance.

                                                In the States my experience has been 2 place decimals are +/_ .01 and 3 Place decimals are +/_ .005

                                                If you want a three palce decimal to be +/_ .01 than it should be noted on the print as .375 +/_.010, if in fact you want a range of .385/.365.

                                                Not as .38 and the tolerance block tolerance of +/- .01 which will bring it up to .39 and down to .37, totally diffrent than above.

                                                In my opinion if you want anything other than what is stated and interpreted from the tolerance block it should be individually noted as a tolerance for that specific dimension.

                                                That applies to both English and Metric.

                                                Just my 20 Yen.

                                                Regards,

                                                B. B.







                                                  • ASME Y14.5 Gurus
                                                    Eddie Cyganik
                                                    Bob,

                                                    Agreed.

                                                    When you mention that they are specifying the tolerance in block form but adjusting to suit the size of the part, then they are doing so by going to the ISO 2768 (or equivalent DIN or JIS) and selecting the tolerance based on size.

                                                    I also agrree with your assessment about trailing zeros, symmetric tolerance and rounding, as it is not just a straight forward affair.

                                                    Lastly, yes you need to place a tolerance on any dimension on the field of the drawing that cannot be satisfied with block or note tolerances.
                                                      • ASME Y14.5 Gurus
                                                        Robert Berry
                                                        Eddie,

                                                        I looked closer at some of the German prints and they actually call out the spec you refer to in the title block, so ISO 2768 would be correct.

                                                        The Japansese tend to put a tolerance block on the drawing that I would guess conforms to the ISO spec or appropriate JIS spec.

                                                        The Japanese also tend to list the fit tolerance they want along with the fit deignation, where the Germans will just say H6 and leave it at that.

                                                        Although not a direct Solidworks discussion, it was interesting none the less.

                                                        Thanks for your input.

                                                        I'm still waiting for the guys who don't use GDT and only the solid model to explain to me how they convey runout, perpendicularity. and paralellism w/o GDT on a model or drawing.


                                                        Best Regards,
                                                        B. B.

                                                          • ASME Y14.5 Gurus
                                                            Matthew Lorono
                                                            Eddie,

                                                            It's been noted by some that ISO 2768 declares itself uninforcable because it says to ignore the tolerances on the part when the part is found to be OK. I'm paraphrasing, but it essentially does say that. It basically assumes the designer isn't even bothering to maintain design intent. In other words, it practically declares itself as "for reference only".
                                                              • ASME Y14.5 Gurus
                                                                Eddie Cyganik

                                                                Matt,

                                                                I have to say, especially coming from you that your response is..., well let me put it this way, not what I expected. You say you are paraphrasing, would you please clarify with a quote or something more substantial?

                                                                I have read through ISO 2768 -1 & -2 and the closest I've come to relating to your comments are:

                                                                Section 6 Rejection
                                                                Unless otherwise stated, workpieces exceeding the general tolerance shall not lead to automatic rejection provided that the ability of the workpiece to function is not impaired (see clause A.4).


                                                                Clause A.4
                                                                The tolerance the function allows is often greater than the general tolerance. The function of the part is, therefore, not always impaired when the general tolerance is (occasionally) exceeded at any feature of the workpiece. Exceeding the general tolerance should lead to a rejection of the workpeice only if the function is impaired.


                                                                The statements above do not, by any means, declare the standards unenforceable nor do they practically declare themselves reference only. Lastly, I do not believe any standard has been written that basically assumes the designer isn't even bothering to maintain design intent. That's absurd!

                                                                ISO 2768-1 & -2 are active, valid and useable standards when interpreted and applied correctly.
                                                                  • ASME Y14.5 Gurus
                                                                    Matthew Lorono

                                                                    Eddie Cyganik wrote:

                                                                     

                                                                    Matt,

                                                                    I have to say, especially coming from you that your response is..., well let me put it this way, not what I expected. You say you are paraphrasing, would you please clarify with a quote or something more substantial?

                                                                    I have read through ISO 2768 -1 & -2 and the closest I've come to relating to your comments are:

                                                                    Section 6 Rejection

                                                                    Unless otherwise stated, workpieces exceeding the general tolerance shall not lead to automatic rejection provided that the ability of the workpiece to function is not impaired (see clause A.4).




                                                                    Clause A.4

                                                                    The tolerance the function allows is often greater than the general tolerance. The function of the part is, therefore, not always impaired when the general tolerance is (occasionally) exceeded at any feature of the workpiece. Exceeding the general tolerance should lead to a rejection of the workpeice only if the function is impaired.


                                                                    The statements above do not, by any means, declare the standards unenforceable nor do they practically declare themselves reference only. Lastly, I do not believe any standard has been written that basically assumes the designer isn't even bothering to maintain design intent. That's absurd!

                                                                    ISO 2768-1 & -2 are active, valid and useable standards when interpreted and applied correctly.

                                                                    Not withstanding your opinion of my absurdity, I disagree with you on this. In fact, your direct quote from the standard actually made my point, at least to some in the community. I suggest that clause in the standard does self-invalidate the standard.

                                                                    The purpose of the standard is to provide standard tolerancing, yet has that clause that is in reference to an uncontrolled quality inspection criteria. Drawings are legal documents that are meant to capture the design intent without ambiguity. QA is an inspection process based on those drawings and internal company processes. That one clause makes the whole process of the documentation open to debate by making quality inspection criteria part of the specification itself (as opposed inspection to being driving by the specification). This creates ambiguity.

                                                                    It also affects the form and fit of a part without the requirement for change control (which is supposed to be a no-no under ISO). I could go on about other issues this one clause creates for the standard. There's plenty of discussion on this on the eng-tips.com board.
                                                                      • ASME Y14.5 Gurus
                                                                        Robert Berry
                                                                        Matt,

                                                                        Your interpretation of the spec is somewhat flawed.

                                                                        You state, "Drawings are legal documents that are meant to capture the design intent without ambiguity."

                                                                        Yes they are, however, that does not exclude a company from making a judgement on a non conforming part and accepting it. The standard states this as an option when the tolerances are not within the letter of the law but are still funtional.

                                                                        You also stated, "which is supposed to be a no-no under ISO".

                                                                        I assume you are talking about the ISO certification agency of which my company is certified and has been for years.

                                                                        We have a document, which is also legal, called a DR (Deviation Request) which allows us to accept or reject parts that are non conforming. This is a part of our ISO procedure and quite acceptable practice for ISO Standards.

                                                                        In the real world non conforming parts are evaluated every day and accepted or rejected based on that non conformitys effect on form fit and function.

                                                                        The standard simply acckowledges that reality and provides for it.

                                                                        This discussion started as GDT, but your attitude tword ISO 2768 is basically the same as those who find excuses to ignore GDT because they don't really like it or could not be bothered to use it.

                                                                        Regards,

                                                                        B. B.


                                                                          • ASME Y14.5 Gurus
                                                                            Barna Madau

                                                                            Bob Berry wrote:

                                                                             

                                                                            ...that does not exclude a company from making a judgement on a non conforming part and accepting it. The standard states this as an option when the tolerances are not within the letter of the law but are still funtional.

                                                                            On this basis then could you conclude that the spec on the drawing is incorrect? And if the parts are indeed usable, that the drawing should be altered to refelct this condition these parts came in with, so future parts would not be out of spec?

                                                                            That was the practice at the companies I've worked. If our spec would cause QC to reject good parts, the spec needed to be changed, and that's what we did.

                                                                            The this would always raise the debate- say you had a non functional feature w/ a callout of say R0.5 MAX. And the part came in w/ a radius of 0.51mm. Do you reject it? no- do you alter the drawing to say R0.51 MAX? Then next time say they came it at 0.52mm?? How far do you go before you draw a line in the sand and reject the part based on a non functional feature? And I guess I've now argued myself full circle in support of ISO 2768 (fyi- I'm not familiar w/ ISO standards...)

                                                                            BM


                                                                              • ASME Y14.5 Gurus
                                                                                Robert Berry
                                                                                Barna,

                                                                                I do not dissagree, I have pondered and discussed this many times.

                                                                                The reality for me is as stated in clause A.4 (noted by Eddie)

                                                                                The tolerance the function allows is often greater than the general tolerance. The function of the part is, therefore, not always impaired when the general tolerance is (occasionally) exceeded at any feature of the workpiece. Exceeding the general tolerance should lead to a rejection of the workpeice only if the function is impaired.

                                                                                That being said, you use your experience, judgement, effect on form fit, and function, Etc.. to make the call.

                                                                                When you design the part you rely on all that kowledge to arrive at the correct tolerance, wether it be a standard, spec or experience. That tolerance may or may not be negotiable and is an acceptable range for the parts to function properly.

                                                                                That does not neccesarily mean they can not function outside that range.

                                                                                For example, a shaft may be a little over size, but the mating part, (which is to size in clearance), will allow the two parts to go together. A little tight but acceptable.

                                                                                Why discard the shaft just because it is oversize?

                                                                                It doesn't make any sense to me, and anyone who will reject that part out of hand is not using much common sense.

                                                                                But then again some companys have more dollars than sense.

                                                                                Just my two cents.

                                                                                Regards,

                                                                                B. B.
                                                                            • ASME Y14.5 Gurus
                                                                              Eddie Cyganik

                                                                              Matthew,

                                                                              No standard is perfect, even ASME Y14.5 has gray areas and others that are left to ones interpretation. I believe if you read the entire standard, you'll see why the rejection & supporting clause were written, well, at least I did but then again we all have our interpretation. Let me say this before I go on, I've been to Eng-Tips before but I cannot get over all the commercialism (flashing, pop-ups, glitz and all, not to mention the, never mind, I'll just get in trouble there.)

                                                                              I'll just say this and be done:
                                                                              I believe the statements provide for some common sense prior to a total rejection or elimination of a part. I based my opinion on the fact that there are documented ranges of tolerance that not only cover the small to the very large (.5mm to 4000mm) but the standard also covers four tolerance classes under ISO2768-1 (fine, medium, course & very course) and three tolerance classes under ISO2768-2 (K-middle, H-higher & L-Looser). We use ISO2768-mK.
                                                                              Because of the ranges & classes, you may have a case at the end of the scale in the 2000 to 4000mm range, say 3800 using the medium (m) tolerance class or ±2, yet the part comes in at +3. Therefore the rejection & clause allow review of the part or one of its features where it is determined to have acceptable functionality. This can be attributed to a machine or a machine shop's capabilities. In this case the review would determine to UAI (Use As Is) or to modify the drawing to specify a larger tolerance on a specific dimension. Although I am not sure if the ASME standard states anything similar to the ISO but in reality, this case could come up regardless of the UOM (Unit Of Measure) and/or the tolerances specified.
                                                                                • ASME Y14.5 Gurus
                                                                                  Matthew Lorono
                                                                                  "I believe the statements provide for some common sense prior to a total rejection or elimination of a part."

                                                                                  I would just like to point out that 'common sense" is an urban legend. One person's common sense is another person's absurdity.

                                                                                  As far as the argument about if it doesn't affect the function, it should still be acceptable: Huh? One example, if several parts within an assembly drift in form over time until they are outside of the stated spec, they may still fit together in a current assembly on the production floor, but they may not fit with parts of the same revision made a year ago. This would create an issue for Service, and directly contradicts the design intent (the whole purpose of having tolerances).

                                                                                  Barna is right about drawings needing to be changed if found to be too strict, and they also need to be followed as the legal documents that they are.

                                                                                  That said, I agree that business needs outweigh the precision of a drawing from time to time. In those cases, the company makes a documented decision to allow exceptions. This is a CAPA issue, not something that should be included in the drawing specification, unless the change is made permanent via a change order. That clause belongs on the CAPA and/or quality inspection standards, not in a drawing specification standard.
                                                                                    • ASME Y14.5 Gurus
                                                                                      Robert Berry
                                                                                      Matthew,

                                                                                      As long as that absurdity is documented and trackable there should be no problem.

                                                                                      "One example, if several parts within an assembly drift in form over time until they are outside of the stated spec, they may still fit together in a current assembly on the production floor, but they may not fit with parts of the same revision made a year ago. This would create an issue for Service, and directly contradicts the design intent (the whole purpose of having tolerances)."

                                                                                      Huh?, what you describe does affect future form, fit and function.

                                                                                      We do alot of one offs, prototypes and in house tooling that may or may not be a candidate for DR (deviation request).

                                                                                      If you want to reject a pilot that is one tenth oversize that fits into a housing that will accept it on a prototype part that is essentially a one off go ahead.

                                                                                      But when you need something from that machinist in the future, be advised he may tell you to go pound sand.
                                                                                        • ASME Y14.5 Gurus
                                                                                          Matthew Lorono
                                                                                          I don't need any particular machinist. If they didn't do the work to the previously agreed to PO (including drawing specifications), they should be held accountable, even if internally their product is found to be acceptable.

                                                                                          Regardless to that, none of what you are suggesting regarding the acceptance of parts is actually in question, as I noted. My point still stands. To accept or reject a part is a function of the quality assurance and CAPA processes. This is not apart of product definition (including design intent). That one clause creates ambitiguity by trying to say that CAPA considerations are part of the product definition itself. It basically says "Ignore the specifications in this document if you find out after the fact that it still works". Would you be willing to put that blanket statement directly on your drawing?

                                                                                          If this clause is invoked, you are asking the part to be manufactured by some criteria that doesn't exist until after the part is manufactured. It's a chicken-and-the-egg scenario. The clause does need to be in the standards. It just should not be in a product definition standard.


                                                                                          Bob Berry wrote:

                                                                                           

                                                                                          Matthew,

                                                                                          Huh?, what you describe does affect future form, fit and function.

                                                                                          You've never seen a company make uninformed, rushed, on-the-fly and underdocumented decisions regarding received product? You are very lucky indeed.
                                                                                            • ASME Y14.5 Gurus
                                                                                              Robert Berry
                                                                                              "I don't need any particular machinist."

                                                                                              We do 80% of our machining in house and all of our prototype machining. If I took that attitude I would not have a very pleasant environment to work in and my jobs would be pushed to the back when ever possible. Not right, but human nature.

                                                                                              Outside vendors are a completely diffrent animal.


                                                                                              "You've never seen a company make uninformed, rushed, on-the-fly and underdocumented decisions regarding received product? You are very lucky indeed. "

                                                                                              Sure I have, but I am not talking about "received product".

                                                                                              "That one clause creates ambitiguity by trying to say that CAPA considerations are part of the product definition itself. It basically says "Ignore the specifications in this document if you find out after the fact that it still works". Would you be willing to put that blanket statement directly on your drawing?"

                                                                                              I agree, but is that reason to disregard the document and claim all of it's content invalid?

                                                                                              No I would not be willing to put that blanket statement on a drawing, just as I am unwilling to disregard the intent of the standard because of one statement.


                                                                                              Regards,

                                                                                              B. B








                                                                                                • ASME Y14.5 Gurus
                                                                                                  Matthew Lorono

                                                                                                  Bob Berry wrote:

                                                                                                   

                                                                                                  I agree, but is that reason to disregard the document and claim all of it's content invalid?

                                                                                                  To me, its only for the fun of pointing out contradictions in the "standards".

                                                                                                  To a lawyer, yes that is enough to claim invalidity. Drawings are part of legal contracts and do get dragged into court (or arbitration) from time to time.

                                                                                                   


                                                                                                  No I would not be willing to put that blanket statement on a drawing, just as I am unwilling to disregard the intent of the standard because of one statement.

                                                                                                  My original comments were provocatively stated, mostly just for fun. Even still, I was pointing out a reasonable interpretation of the standard where it can be said to be making its own self-invalidating statement. Further, I didn't come up with this POV on my own. Some might say I'm just not that smart.
                                                                        • Re: ASME Y14.5 Gurus
                                                                          Todd Pederzani

                                                                          Bob, I'm in search for a standard for converting between units.  The DIN 370 you mention would be great, but I can't find mention of it on DIN's website.  Is that the right standard number for it?

                                                                           

                                                                          (sorry to bump such an old thread.)

                                                              • ASME Y14.5 Gurus
                                                                Eddie Cyganik

                                                                Barna,

                                                                Number one, it really isn't a good idea to ask two unrelated questions under one topic, for obvious reason.

                                                                I will address the topic listed, ASME Y14.5M.

                                                                I do agree with Steve, there isn't any standard that I know of that covers dual dimensioning, let alone dual dimensioning of basic dimensions. The practice would have a multitude of problems, most notably conversion method (A or B). Then of course there is the issue would of what dimensions to use for machining, inspection, etc.

                                                                Every place that I have ever worked, where dual dimensioning was used, had a Drafting Room Manual that had a section outlining the procedures to follow for dual dimensioning.

                                                                Currently, we only use dual dimensions on our interface drawings and only upon special request from the customer.

                                                                The only thing I can say for sure is that every facet of a dimension was treated a an entirely separate entity when displaying its dual counterpart.
                                                                • ASME Y14.5 Gurus
                                                                  Paul Lemke
                                                                  Get em, Bob. Such is the end of any destruction of mental thought against progress. The fundamental tenet: that they don't want to learn another system, leads to their own problems. Classic. I am sure now of course they want you to find a way to make both possible.

                                                                  Real objective logic and abstracts are inescapable and I think the ASME GD&T committees knew this. Dual dimensioning is crap and that is why the standard doesn't cover it. A widget's physical measuring system is a basis and an AXIOM on which all of its corresponding parts must be developed. Fit and form, cause and effect, a concept-ual basis of reality.

                                                                  Of course all of these problems are design problems because that is where theoretical thought, engineering, meets reality, actually manufacturing something into reality. It is interesting that this is similar in scope to the GD&T thread. Another core basis of y14.5 1.4(a): Each dimension shall have a tolerance, except for those dimensions specifically identified as reference, maximum, minimum or stock.
                                                                  A.K.A. if your going to manufacture it you don't do it perfectly and lets control that variation. I am surprised however that the fundamental rules of y14.5 are not plastered all over shop walls and engineering departments. They should make wallpaper.
                                                                  • ASME Y14.5 Gurus
                                                                    Paul Lemke
                                                                    I have not studied ISO, but looking at the economy and how much inflation there will be, maybe I should, because I will have to move over seas in order to find a job in manufacturing and design. Steve what are the primary documents of ISO?
                                                                      • ASME Y14.5 Gurus
                                                                        Eddie Cyganik

                                                                        Paul,

                                                                        One of the major problems with following ISO standards is the sheer number of standards required. Go to the ISO website and perform a search on "technical drawings" just to get an idea.

                                                                        When we started our research into creating what we dubbed our "international" ISO (DIN & JIS) drawing formats (back in 2003) we ended up buying three things;


                                                                        1.) ISO 128 - Technical Drawings - General principles of presentation



                                                                        2.) Technical Drawings Vol. 1 Technical drawings in general
                                                                        Technical Drawings Vol. 2 Mechanical engineering / construction drawings / drawing equipment

                                                                        3.) Handbook on CD for metric "Fasteners & Screws".

                                                                        Total cost, approx $650.
                                                                          • ASME Y14.5 Gurus
                                                                            Dwight Livingston
                                                                            All

                                                                            Before looking it up just now, I didn't know that ASME Y14.5M-1994 requires ISO-type formatting for metric measures, which, as Barna says, means that you can't use places beyond the decimal point to indicate tolerance. So are there any ASME rules about tolerance in that case, or is a tolerance suffix pretty much required? Is it an ASME standard to invoke ISO?
                                                                              • ASME Y14.5 Gurus
                                                                                Eddie Cyganik

                                                                                Dwight,

                                                                                I do not see where Barna said anything about not using any decimal place for tolerances. Or maybe you misunderstood what someone else said.

                                                                                In any event, nowhere in ASME or ISO is there anything that prohibits tolerances applied to metric dimensions. You could very well have a one place metric dimension, toleranced as follows:
                                                                                246.4±.1
                                                                                as well as a two place metric dimesion, toleranced as follows:
                                                                                39.75±.05

                                                                                As far as ASME Y14.5M rules go, they are what they are and they apply to "metric" as the "M" indicates.

                                                                                Lastly, I do not know of any ASME standard that calls or involkes an ISO standard or vers-vicea.

                                                                                PS Note: ISO 2768 -1, -2 & -3 all satisfy tolerancing requirements based on a feature or measurement "size" and "tolerance class". So indication of tolerance is not required regardless of the number of decimal places.

                                                                                PSS Note2: When used, ISO 286-2 (FIT Tolerancing) can be specified using tolerance values, the FIT designator or both and once again, tolerancing requirements are defined and specified based on a feature or measurement "size" and "fit class".
                                                                                  • ASME Y14.5 Gurus
                                                                                    Robert Berry
                                                                                    Eddie,

                                                                                    It's been my experience, (not sure if it's in the standard), that dimensions less than one millimeter are designated with a 0 before the decimal point.

                                                                                    Such as 0.1, wether it is for a base dimension or tolerance.

                                                                                    I would look it up to confirm but as it is Friday and I am leaving early to start drinking heavily someone else can check.

                                                                                    B. B.
                                                                                      • ASME Y14.5 Gurus
                                                                                        Barna Madau

                                                                                        Bob Berry wrote:

                                                                                         

                                                                                        Eddie,



                                                                                        It's been my experience, (not sure if it's in the standard), that dimensions less than one millimeter are designated with a 0 before the decimal point.



                                                                                        Such as 0.1, wether it is for a base dimension or tolerance.



                                                                                        I would look it up to confirm but as it is Friday and I am leaving early to start drinking heavily someone else can check.



                                                                                        B. B.

                                                                                        You are correct- per ASME Y14.5 M1994 paragraph 1.6.1(a)

                                                                                        enjoy your drinking...

                                                                                        BM

                                                                                        • ASME Y14.5 Gurus
                                                                                          Eddie Cyganik

                                                                                          Bob,

                                                                                          I agree;
                                                                                          Add a leading zero for under 1mm this is done to make the decimal poit or comma more visible:
                                                                                          0,5 or 0.5 is clearer than ,5 or .5 (This is especially true if dimension values have text or are used in a note, example
                                                                                          SPOTFACE 0,5 DEEP TO FULL DIAMETER MAX.
                                                                                          ---versus---
                                                                                          SPOTFACE ,5 DEEP TO FULL DIAMETER MAX.

                                                                                          Also, trailing zeros are droped.

                                                                                          Note: I believe These are universal "metric" things.

                                                                                        • ASME Y14.5 Gurus
                                                                                          Barna Madau
                                                                                          My problem, even with regards to inch dimensions w/ standard tolerance blocks are in the case of- .XXX = +/- .005, .XX = +/- .010 (for example), and say your nominal dimension is .375 but you want to place a +/- .010 tolerance on it. Rounding it to two decimal won't work, because you would then be in essence making your tolerance +.015/-.005.

                                                                                          I've made it a practice to use limit tolerances on all my drawings, so the machinist isn't reaching for his calculator and pencil in the limits (which I've seen many of them do).

                                                                                          Which brings up another point, SW is pretty bad about supressing trailing zeros when usign limit tolerances. It defaults to the document tolerance presision. For example, (I haven't tried this recently, so forgive me if this issue has been resolved)- Say you have a dimension of 5mm, and you tolerance it +/- 0.1mm (5.1/4.9 on the drawing) but then go back, edit your model and make the dimension 5.05mm. Then, SW (at least used to) would retain 1 decimal palce tolerance precision, and just round the dimension on the drawing to (5.2/5.0) rather than automatically seeing there's a need ot change the precision to two decimal places (5.15/4.95). This creates the impossible task of going back through every dimension in a drawing and make sure the proper number of decimal places are being shown every time you make a model edit. So, our workaround was to violate the standard and show all toleranced dimensions as two decimal place (ashamed to say it).

                                                                                          BM
                                                                                            • ASME Y14.5 Gurus
                                                                                              Eddie Cyganik

                                                                                              Barna Madau wrote:

                                                                                               

                                                                                              My problem, even with regards to inch dimensions w/ standard tolerance blocks are in the case of- .XXX = +/- .005, .XX = +/- .010 (for example), and say your nominal dimension is .375 but you want to place a +/- .010 tolerance on it. Rounding it to two decimal won't work, because you would then be in essence making your tolerance +.015/-.005.

                                                                                              If you have a 3 place dimension that can be ±.010 then simply mark it as such on the field of the drawing. No problem. Why would you want/need to do any rounding? And what does +.015/-.005 have to do with anything?



                                                                                               

                                                                                              I've made it a practice to use limit tolerances on all my drawings, so the machinist isn't reaching for his calculator and pencil in the limits (which I've seen many of them do).

                                                                                              This really doesn't make any sense as your design requirement/mean dimension will not be displayed. Example if you have an o-ring groove, the catalog dimension could be:
                                                                                              1.062 +.008/-.000
                                                                                              To start with, a machinist would be shooting for 1.062 knowing if they go over, they are still in the ballpark.

                                                                                              If you specify 1.062/1.070, what will he shoot for? If you say the middle, then out comes the calculator.


                                                                                               

                                                                                              Which brings up another point, SW is pretty bad about supressing trailing zeros when usign limit tolerances. It defaults to the document tolerance presision. For example, (I haven't tried this recently, so forgive me if this issue has been resolved)- Say you have a dimension of 5mm, and you tolerance it +/- 0.1mm (5.1/4.9 on the drawing) but then go back, edit your model and make the dimension 5.05mm. Then, SW (at least used to) would retain 1 decimal palce tolerance precision, and just round the dimension on the drawing to (5.2/5.0) rather than automatically seeing there's a need ot change the precision to two decimal places (5.15/4.95). This creates the impossible task of going back through every dimension in a drawing and make sure the proper number of decimal places are being shown every time you make a model edit. So, our workaround was to violate the standard and show all toleranced dimensions as two decimal place (ashamed to say it).

                                                                                              BM

                                                                                              This is getting way off-track.
                                                                                              If you'd like to start a separate topic on this then go ahead and I'll reply to it.
                                                                                                • ASME Y14.5 Gurus
                                                                                                  Barna Madau

                                                                                                  Eddie Cyganik wrote:

                                                                                                   

                                                                                                  If you have a 3 place dimension that can be ±.010 then simply mark it as such on the field of the drawing. No problem. Why would you want/need to do any rounding? And what does +.015/-.005 have to do with anything?

                                                                                                  .375 +/- .010 is .385/.365. If you round .375 two decimal places you get .38, at .XX = +/-.010 results in .390/.370. .390 is .375 +.015, .370 is .375 -.005. To have the two decimal - +/- .010 in the tolerance block but still have to put +/- .010 on some dimensions that just happen to need three decimal places to prevent rounding up or down seems redundant and stupid. Just bugs me.


                                                                                                  Eddie Cyganik wrote:

                                                                                                   

                                                                                                  If you specify 1.062/1.070, what will he shoot for? If you say the middle, then out comes the calculator.

                                                                                                  Every machinist I've worked w/ shoots for MMC. You can always take a bit extra off, but it's usually pretty hard to put any back on. Not rocket science.

                                                                                                  BM

                                                                                                  EDIT: Attached example
                                                                                                    • ASME Y14.5 Gurus
                                                                                                      Eddie Cyganik

                                                                                                      Barna,

                                                                                                      One more time.

                                                                                                      I really don't uderstand, if you have .375 as a design dimension and per your design layout with tolerance stack-up, you determine that the .375 can have a ±.010 tolerance, then put this design information on your drawing.

                                                                                                      So my question remains, "Why are you rounding?"

                                                                                                      There is absolutely nothing wrong with block tolerances being:
                                                                                                      .X±.1 .XX±.03 .XXX±.005

                                                                                                      and several dimensions that have a specific tolerance on the drawing:
                                                                                                      .750±.030
                                                                                                      or
                                                                                                      .750±.100
                                                                                                      ...all 3 decimal places means is to inspect to a minimum of 3 decimal places to verify.

                                                                                                      It is now well past BEER:30, so I'm outta here!
                                                                                                      Have a great weekend, we'll give hell again on Monday.
                                                                                            • Re: ASME Y14.5 Gurus
                                                                                              Matthew Lorono
                                                                                              In addition to the costs, there are other problems with ISO.  The ISO standards are not 100% truly international; they can (and some do) vary between regions.  Another problem is in the dimensional/tolerance defaults.  Rule #1 is implied on any ASME based print.  It is not implied on any ISO based prints.  If the U.S. based engineering staff is not careful when working under ISO and they are not aggressively using GD&T, this could lead to some pretty embarrassing nonconformances or even lawsuits.  Essentially, an ASME drawing says what you expect to receive as the final product, and an ISO drawing says what you hope to receive as the final product.