I don't disagree, Norm, but they had to do something to address the 3-D CAD environment. Really, the other standards should be revised to address the 3-D environment.
I can understand the attempt to address the 3D environment. However, must of the "requirements" simply are not value added. For example, why is that we can not use an extension line for feature control frames or datum feature symbols? In 3D, using the common 2D extension line permits numerous advantages. One, more of the GD&T can be more organized and displayed in a single view.
Why is it that most if not all the annotation has to be in the same plane, a parallel plane, or perpendicular plane to the feature? Who cares? It is 3D.
Why does a leader line have to end in a DOT when associated to a surface? In 2D it makes sense, but in 3D; What is the value? These sort of details are only going to lead to a pile of human errors frustrating people who want to implement 3D annotation.
The standard has an exception for leaders to point to edges of "features of size" if it provides a clearer understanding. Why not surfaces? For example a profile of surface(s)? I know that the leader can also just point to the surface(s) with the DOT, but consider acceptance of 3D annotation. When within a "model view" that represents a 2D view, it makes sense to use a leader to an edge like we have done in 2D forever so that when the "model view" is shown or even printed, it looks like what the world is used to. Meanwhile, in 3D the queries clearly identify the features that belong to the annotation. Again, why do we need dots?
The query requirements are another major issue, but that is another thread, I am sure.
Some of what write here may seem petty. But to people putting the annotation on only to have to edit it or adjust a default etc etc to control dots over arrowheads, pointing to surfaces instead of edges (which I don't particularly like, but don't think it should be illegal), and the whole relative plane thing is going to slow 3D annotation down reducing it's major benefit, TIME.
I would love to get on the 14.41 committee. I've been doing 3D annotation for over 10 years and it just seems like the standard has choked some of the benefit with these details. IMHO
My opinion is that 14.41 was made in a vacuum without regard to 3D CAD applications available. It seems as though they had one person or body of people familiar with some ancient application who wrote the standard.
I participate on the 14.41 S/C now, either on the support team or maybe as a member now ... I'm not sure what was decided after the last meeting. Anyway, I do understand everyone's frustration, and here's what I've gleaned of the standard's history.
IN THE BEGINNING, there were no standards governing the means of 3D drafting ... and manufacturing, design and military industries saw that this was bad. Each CAD company seemed to be taking their own path, with no commonality or consideration of industry as a whole; they either reflected their primary clients' wishes or went however they wanted ... and that was worse. Similar to the recognized need for a mathematical standard for ASME GD&T (Y14.5.1) to establish a common baseline, so it was with CAD capabilities. A couple of software suppliers participated in the original 14.41 development, but only one continues participation today. Some things make sense in the standard, and others do not necessarily, often because of the reader's own background & biases (for better & for worse). The issue of putting the leader on the surface vs on an edge seems trivial, but it was/is a substantial issue for CAD software and for graphical outputs. While most of us are of a background based on using 2-D drawing layouts where the edge is shown, a print made from a 3-D annotated model does not have to be shown in those classical views, and therefore a leader to any edge may be indicating either of the surfaces abutting it. Dot vs arrow ... trivial to me, but makes consistency in CAD much easier. Old software represented solids as wireframe geometries, with no attributes for what we visualized as the surface; if there's no attributes, then the leader couldn't be attached, hence all annotation was done to edges. To drive the software development, a requirement had to be put in place.
I was stuck helping to develop company drafting standards/practices and had to enforce them; what I found pretty much uniformly was that the detailers were pressed for time and didn't care enough about their product (i.e. the print) to worry about the rules. That doesn't mean the rules are at fault. Putting a dot on the end of a surface leader is no different from putting a capital letter on the first word of a sentence ... it's just a rule that you get used to and follow. In a legal contract that may be enough to change the meaning of an entire clause.
Personally, I find 3-D annotation in most packages to be ineffective and so difficult and time consuming as to be worthless. Comparing the package methodologies to the Y14.41 standards shows little in the way of adherence, but things are changing for the better as the new software engines and model databases are developed and implemented.
As far as I know, Norm, there's still seats at the table in Y14.41, and they don't make the support team sit at the kids' table either.
OK Jim, I am in if I can get invited to the Y14.41 table. But I forget now just who to contact directly.
With regard to the leaders, I just want to summarize that there is room in a standard for "practices" and certainly meanings. That is to say; "know what a dot at the end of a leader means when used." I don't think it should be "required" to be used in 3D because of the overlapping requirements for "queries", which is yet another whole issue.
Most fundamental to me, in my personal opinion, is that the Y14.41 standard needs to be the future and what I am saying is that there should be no relevance to 2D drafting practices. In other words, lets stop making 3D look like 2D. That is exactly what reduces the time saving value of 3D annotation and "complicates" it's use and thus not as widely accepted as it really can be.
Lastly, although I having many thoughts for enhancement of the Y14.41-2003 standard and simply do not like some of what is in there, I have publically applauded the committee in the past and am doing so again for taking the first step in developing a standard that will live on. The pluses far outway the negatives!
As the OP, I have followed this thread with much interest, much of which seems to be discussing standards written for 3D work. I should probably have phrased my original question differently: Are there leader standards for 2D and 3D drafting? For instance, in 2D drafting, should the text be justified towards the arrow, should the last leader line be horizontal, should the leader be attached to the first, middle or under the text, are the rules the same for right and left hand leaders, etc. Is there one set of standards for 2D and another for 3D? Do any of the AutoCAD templates adhere to any standards for leaders?
IFRs, I haven't seen a specific "leader" standard with the details you seek. On the other hand, Y14.5 requires that the text be readable when viewed from the bottom of the drawing sheet; this is supported graphically throughout the Y14.5 standard, and further illustrates that the short leader extension from the annotation comes horizontally from it, then extends to the indicated feature. Y14.41 does not disagree with this, but shifts it to legible on the annotation plane (essentially a virtual "sheet"). As far as I know, the rest are all typically best practices rather than documented standards.
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