【转帖】using asme y14.41 and asme y14.5

yang686526

using asme y14.41 and asme y14.5
we use autodesk inventor which is very limited in it's ability to adhear to asme y14.41 but we would like to use it as much as possible. we have some cast, industrial design parts that have complex curves and radii. this makes it extremly difficult to dimension per asme y14.5 (our usual standard). what i would like to do is dimension the majority of the features per y14.5 and then provide a note linking the drawing to the model for definition of the complex features. has anyone been working to y14.41? is it legal to reference both standards on a single drawing? as near as i can tell from reading the standard, i can dimension everything on the 2d drawing and query the model for anything not dimensioned per y14.41, but do you then call out y14.5 as the standard for interpreting the dimensions on the 2d print?
thanks for your help.
david
check out our whitepaper library.
you can call out whatever standard is needed and follow each as needed. clarify in notes. as long as the dwg is clear and understandable.
chris
solidworks 06 5.1/pdmworks 06
autocad 06
while we may follow 14.41 to a certain degree, we only specify 14.5 on the drawing.  we include a note stating that the model is the engineering master defintion and takes precedence, and any undimensioned features are to be derived from the model.  we add additional (is that redundant?) notes explaining the tolerancing which applies to model derived dimensions.
as ctopher posts, the main thing is to make sure that the drawing is clear and unambiguous.
i've been using a y14.41 note only.  since y14.41 references y14.5 i think it would be implied, no?
most of my work has been models w/ drawings only for notes, etc.
aardvarkdw,
   how are you planning to inspect this thing?
   i have not run into this problem yet, but probably, i am headed there.  i am assuming i will show section views with grids imposed on them, and that i will use these to create inspection templates.  this would make asme y14.5m work, and it would allow an inspector to work off of our 2d drawings.
   i have not tried any of this yet.
                      jhg
drawoh,
i'm not sure, we are still working on that. right now we don't inspect them and that is half of the problem. on the complex parts we have done in the past, the drawing has shown had ortho views of the part with pem fastener notes and a note saying "all dimensions and shapes defined by solid model xxx-xxxxxx-xxx." this has been a problem for us because we don't have a cmm and our qa people can't inspect from the model file. we have been getting parts that "seem" to meet spec but our problem is in controlling our files. we don't archive the native files and we have had really poor file control. basicly anyone with inventor can edit the models (and do). on top of that these parts are often created from a rhino .igs file and have errors beyond belief. i am instituting drafting standards and practices to eliminate some of these problems but nothing is perfect. where this particular problem comes from is that we sometimes have major catastrophies with these parts when changes need to be made (because of poor drafting practices) and we need to rebuild the part from scratch. interpreting the part from a .step file is cumbersome. so, i want our designers to put as many design details on the print as they can. this way we can inspect the mating features and recreate the part if need be.
david
aardvarkdw,
   it sounds like you need pdm to control your files.
   my biggest concern about asme y14.41 is that your inspectors need a lot of access to the 3d model.  this all starts to work if you have a cmm.  if you have a granite reference block, a height vernier and all sorts of fixtures, you need a process.  the old fashioned 2d piece of paper can be redlined and highlighted as the inspector goes over everything.
                 jhg
drawoh is correct about one of the largest problems with implementing 14.41 - inspection.  without a cmm, it is very difficult to do.  even with one, there are some problems that need to be worked out before it is efficient (wcs location for example).  the best, albeit most expensive route is to have a cmm that can read native cad files.  some of the cad programs have the capability to embed the gd&t which can then be read by the cmm, and that makes the inspectors life much easier. parts go through much faster and problems are detected much earlier.
which is why we haven't implemented it before now and don't intend to jump in with both feet right away when we do. i just know that all features must be dimensioned per asme y14.5m-1994, and that coordinate plotting is not a good option. so to apease our engineers and document control, using y14.41 in addition to y14.5 is my solution. it doesn't solve the inspection problems, but until we get software that can place the gdt on the model and a cmm to inspect with all i can do is fix what i can.
thanks for the sanity check!
david
aardvarkdw,
   if you cannot inspect it, what is the point?
                        jhg
there isn't much of a point except that we need to document the design somehow, otherwise we are reciving parts that we can't inspect and we don't know what they were even supposed to be in the first place. at least be doing this we will know what they should be. it's not a good solution but it is what we can get. the goal is that we can inspect the features that are dimensioned on the print and anything that is only dimensioned from the model is only a cosmetic feature anyway. right now all the features are dimensioned from the model (sort of) and we can't inspect anything.
if the feature needs to mate with something else we will dimension it on the print, even if that means plotting coordinates. if we don't care, because it is a cast cosmetic feature, we will just do what we have done all along and "assume" the part is right.
david